Making use of the temperature data from 53 stations in Liaoning Province in April from 1961 to 2010 and the data of 500 hPa height field and sea surface temperature issued by National Climate Center,the characteristic...Making use of the temperature data from 53 stations in Liaoning Province in April from 1961 to 2010 and the data of 500 hPa height field and sea surface temperature issued by National Climate Center,the characteristics of temperature,sea surface temperature(SST) and 500 hPa height field in April in 2010 were analyzed.The results showed that the anomalously lower temperature in April in 2010 was mainly caused by the anomalous Arctic Oscillation(AO),so as to provide scientific basis for short-term climate prediction.展开更多
High-quality reservoirs occur in the middle-shallow horizons of the northern Songliao Basin. The distribution and genesis of their anomalously high porosity zones were studied using measured porosities, examination of...High-quality reservoirs occur in the middle-shallow horizons of the northern Songliao Basin. The distribution and genesis of their anomalously high porosity zones were studied using measured porosities, examination of ordinary thin sections and blue epoxy resin-impregnated thin sections and by SEM. The results show that there are three anomalously high porosity zones at the depth of 450-900 m, 1,300-1,900 m, 2,050-2,350 m respectively, named zone i, zone ii and zone iii from top to bottom. Horizontally, zone i and zone ii are distributed all over the basin except in the Southeastern Uplift, while zone iii is only distributed in the Central Depression. Zone i was formed by meteoric water leaching as well as organic acid dissolution. Zones ii and iii were dominantly formed by organic acid dissolution. Additionally, clay mineral transformation generating H＋ and hydrocarbon emplacement retarding the cementation of sandstones are also important for the formation of zones ii and iii.展开更多
The description of experimentally observed phenomenon of abnormally high electrical conductivity—'superconductivity' (SC) at the room and higher temperatures is represented. The effect was observed in metalli...The description of experimentally observed phenomenon of abnormally high electrical conductivity—'superconductivity' (SC) at the room and higher temperatures is represented. The effect was observed in metallic monospirals of small radius curvature with high density and regular distribution of dislocations. Transition into state of SC has been observed experimentally in the range from –50 up to 3000°C at the density of transmitting current up to 2·109 A/cm2. The experimental data confirming the watched phenomenon are represented. The explanations of this phenomenon are being proposed in the framework of the dislocation model.展开更多
In the present letters we study the propagation of smooth pulses in anomalously dispersive media. We prove that non-analytical but smooth points in a pulse still propagate with the vacuum speed of light, c. It gives a...In the present letters we study the propagation of smooth pulses in anomalously dispersive media. We prove that non-analytical but smooth points in a pulse still propagate with the vacuum speed of light, c. It gives an upper limit for signal velocity as well as the non-continuous points of the envelop of a pulse or its derivatives of arbitrary order do.展开更多
Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with pha...Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.展开更多
Fe_(3)Sn_(2),a ferromagnetic metal with a kagome lattice,serves as an ideal platform for exploring topological electronic states and Berry curvature due to its unique band structure.However,systematic reports on the t...Fe_(3)Sn_(2),a ferromagnetic metal with a kagome lattice,serves as an ideal platform for exploring topological electronic states and Berry curvature due to its unique band structure.However,systematic reports on the transport properties of Fe_(3)Sn_(2)nanosheets remain scarce.We present temperature-dependent transport property measurements of Fe_(3)Sn_(2)nanosheets synthesized via chemical vapor deposition on Si/SiO_(2)substrates.The samples exhibit a robust anomalous Hall effect from 40 K to 300 K,along with a magnetoresistance sign reversal at 40 K at high magnetic fields,indicating a spin reorientation from in-plane to out-of-plane.Notably,a sharp crossover in the dominant transport contribution from electrons to holes near 200 K is observed,accompanied by distinct anomalous Hall behaviors in the two regimes,indicating a temperature-induced Lifshitz transition within the multi-band system.This divergence is potentially linked to a topological reconstruction of the Fermi surface across the transition.Our findings highlight the tunability of topological transport in two-dimensional kagome magnets and provide new insights into the interplay between band topology,dimensionality and magnetic order.展开更多
Kagome magnets are of growing interest due to their topological electronic structures and unconventional magnetic behavior.Here,we report on the anomalous Hall effect(AHE)in the kagome ferromagnet MgMn_(6)Sn_(6),which...Kagome magnets are of growing interest due to their topological electronic structures and unconventional magnetic behavior.Here,we report on the anomalous Hall effect(AHE)in the kagome ferromagnet MgMn_(6)Sn_(6),which has a Curie temperature of~290 K and an in-plane easy magnetization axis.Magnetotransport measurements show a positive magnetoresistance(MR)below 50 K,which becomes negative at higher temperatures.An intrinsic anomalous Hall conductivity of 114 S·cm^(-1)is observed in MgMn_(6)Sn_(6) single crystals,consistent with ab initio calculations.Moreover,theoretical predictions indicate that shifting the Fermi level(EF)upward by~70 meV could enhance the AHE to~528 S·cm^(-1).These results position MgMn_(6)Sn_(6) as a promising and tunable platform for exploring topological magnetism and related electronic phenomena.展开更多
This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the i...This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the increase of light amplitude;(Ⅳ)Formalism for light-induced anomalous Hall effects.展开更多
We report on the growth of CoFe_(2)O_(4)/Pt heterostructure and their magnetotransport properties.The magnetoresistance under high magnetic fields exhibits a sign change when the temperature increases from 5 K to 10 K...We report on the growth of CoFe_(2)O_(4)/Pt heterostructure and their magnetotransport properties.The magnetoresistance under high magnetic fields exhibits a sign change when the temperature increases from 5 K to 10 K.The anomalous Hall resistance decreases as the temperature increases.Furthermore,angle-dependent magnetoresistance indicates that the observed magnetotransport behaviors originate from the competition between the spin Hall magnetoresistance and magnetic proximity effect.展开更多
Since the 21st century,the Huang–Huai–Hai River Basin(HHHRB)in China has experienced increased frequency and severity of drought–flood abrupt alternation(DFAA)events during early summer,characterized by droughts in...Since the 21st century,the Huang–Huai–Hai River Basin(HHHRB)in China has experienced increased frequency and severity of drought–flood abrupt alternation(DFAA)events during early summer,characterized by droughts in June followed by floods in July.The 2024 event was the most severe since 1981.This study demonstrates that such compound extreme events are closely linked to anomalous subseasonal evolution of large-scale atmospheric circulation.During the drought phase,the East Asian subtropical westerly jet(EAJ)shifts southward,and the western Pacific subtropical high(WPSH)exhibits anomalous strengthening with its western ridge line displaced southward.The flood phase is characterized by acceleration of the EAJ,westward extension of the WPSH,and enhanced southwestern moisture transport from the western Pacific.Beyond these typical features,the 2024 early summer circulation exhibited unique characteristics:Anomalous northeastward intensification of the WPSH facilitated merged moisture influx from both the Indian Ocean and the western Pacific along the southeast pathway into the HHHRB in July,resulting in the highest net moisture inflow at the southern boundary of the HHHRB since 1981.The synergistic effects of multiple factors primarily explain the exceptionally intense DFAA event in 2024.展开更多
The emission of anomalous X-ray pulsars(AXPs)and soft gamma-ray repeaters(SGRs)is believed to be powered by the dissipation of their strong magnetic fields,which coined the name“magnetar”.By combining timing and ene...The emission of anomalous X-ray pulsars(AXPs)and soft gamma-ray repeaters(SGRs)is believed to be powered by the dissipation of their strong magnetic fields,which coined the name“magnetar”.By combining timing and energy observational results,the magnetar model can be easily appreciated.From a timing perspective,the magnetic field strengths of AXPs and SGRs,which are calculated under the assumption of dipole radiation,are extremely strong.From an energy perspective,the X-ray/soft gamma-ray luminosities of AXPs and SGRs are larger than their rotational energy loss rates(i.e.,L_(x>E_(rot)).It is thus reasonable to assume that the high-energy radiation comes from magnetic energy decay,and the magnetar model has been extensively discussed(or accepted).However,we argue that:(ⅰ)Calculating magnetic fields by assuming that rotational energy loss is dominated by dipole radiation(i.e.,E_(rot)■E_(μ))may be controversial,and we suggest that the energies carried by outflowing particles should also be considered.(ⅱ)The fact that X-ray luminosity is greater than the rotational energy loss rate does not necessarily mean that the emission energy comes from the magnetic field decaying,which requires further observational testing.Furthermore,some observational facts conflict with the“magnetar”model,such as observations of anti-magnetars,high magnetic field pulsars,and radio and X-ray observations of AXPs/SGRs.Therefore,we propose a crusted strange star model as an alternative,which can explain many more observational facts of AXPs/SGRs.展开更多
Berry curvature describes the intrinsic geometric property of electronic band structure,crucial for governing emergent transport phenomena.As a typical Berry-curvature-related property,the anomalous Nernst effect prob...Berry curvature describes the intrinsic geometric property of electronic band structure,crucial for governing emergent transport phenomena.As a typical Berry-curvature-related property,the anomalous Nernst effect probes local Berry curvature near the Fermi surface,whereas the anomalous Hall effect integrates contributions across all occupied states.Thus,the anomalous Nernst effect is a superior probe for detecting subtle evolution of Berry curvature near the Fermi level;however,their relation remains elusive.Here,we demonstrate giant anomalous Nernst angles induced by Berry curvature in layered itinerant ferromagnets Fe_(3)GaTe_(2)and Fe_(5)GeTe_(2).Their maximum values(≈0.33 for Fe_(3)GaTe_(2)and≈0.41 for Fe_(5)GeTe_(2))are one order of magnitude larger than those of traditional ferromagnets(θ_(AN)^(max)<0.02).Scaling analysis of anomalous Hall effect in these two systems further suggests these giant angles originate from intrinsic Berry curvature.These findings indicate Berrycurvature-dominated regimes,and establish these materials for high-performance spin-caloritronic devices.展开更多
Altermagnetism,a recently identified class of collinear magnetism,combines key features of antiferromagnets and ferromagnets.Despite having zero net magnetization,altermagnetic materials exhibit anomalous transport ef...Altermagnetism,a recently identified class of collinear magnetism,combines key features of antiferromagnets and ferromagnets.Despite having zero net magnetization,altermagnetic materials exhibit anomalous transport effects,including the anomalous Hall,Nernst,and thermal Hall effects,as well as magneto-optical Kerr and Faraday effects.These phenomena,previously thought unique to ferromagnets,are dictated by symmetry,as confirmed by density functional theory(DFT)calculations.However,an effective model-based approach to verify these symmetry constraints remains unavailable.In this Letter,we construct a k·ρ model for d-wave altermagnets CuX_(2)(X=F,Cl)using spin space group representations and apply it to calculate the anomalous Hall effect.The symmetry-imposed transport properties predicted by the model are in agreement with the DFT results,providing a foundation for further investigation into symmetry-restricted transport phenomena in altermagnetic materials.展开更多
Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodi...Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodicity.Here,we provide both numerical and analytical evidence that a depth gradient metasurface can achieve discrete ultra-broadband perfect anomalous reflection in the microwave range in the absence of geometric periodicity.Remarkably,by adjusting the operating frequency of the incident wave,the same effect can be steadily obtained via a physically equivalent phase periodicity in the PGM.Based on this mechanism,a perfect retroreflector with a broadband response ranging from 1 GHz to 40 GHz is realized.Our work has promising applications in communication,source tracking,and military satellites.展开更多
Dear Editor,We describe a case diagnosed with exudative perifoveal vascular anomalous complex(ePVAC)successfully treated with focal laser photocoagulation(577 nm),achieving a favorable prognosis with best-corrected vi...Dear Editor,We describe a case diagnosed with exudative perifoveal vascular anomalous complex(ePVAC)successfully treated with focal laser photocoagulation(577 nm),achieving a favorable prognosis with best-corrected visual acuity(BCVA)of 20/20.Additionally,we discussed the identification of a possible early-onset non-ePVAC.The ePVAC is characterized as an isolated,aneurysmal abnormity near the macula and usually accompanied by cystic macular edema(ME)[1-2].展开更多
Chemically complex intermetallic alloys(CCIMAs)have emerged as promising materials tor achieving ex-ceptional softening resistance at elevated temperatures,owing to their unique superlattice structures and elemental s...Chemically complex intermetallic alloys(CCIMAs)have emerged as promising materials tor achieving ex-ceptional softening resistance at elevated temperatures,owing to their unique superlattice structures and elemental synergism.However,the lack of experimental endeavors and understanding regarding their temperature-dependent mechanical behaviors hinders their advancement for high-temperature applica-tions.Here,we conducted a systematic investigation on the mechanical properties and associated defor-mation mechanisms of an L12-type Co-rich CCIMA using transmission electron microscopy.The Co-rich CCIMA exhibits superior strength across a wide temperature range of 700-900℃,with an anomalous peak yield strength(YS)of~1.0 GPa at 700℃,which surpasses most previously reported L12-type inter-metallic alloys.This superior softening resistance can be primarily attributed to a combination of cross-slip hardening and segregation-assisted hardening.Specifically,massive Kear-Wilsdorf(K-W)locks formed by multiple cube cross-slips of screw dislocations prevail at 700-900℃,providing strong barriers for dis-location movements and enhancing the yield strength(YS)accordingly.More interestingly,we revealed a segregation-assisted formation of superlattice stacking faults and nanotwins at the peak yield tempera-ture(700℃).The interlocking of these substructures and the associated element dragging effect further impeded the propagation of dislocations,contributing to the observed yield anomaly.This work provides in-depth insight into the high-temperature performance and deformation behaviors of CCIMAs,which paves the way for the future development of novel heat-resistant structural alloys.展开更多
A statistical analysis of the twinning behavior in a basal-textured Mg sheet under hard orientation loading was performed at strain rates of 1×10^(-5) and 1×10^(-1) s^(-1) with grain sizes of 70 and 20µ...A statistical analysis of the twinning behavior in a basal-textured Mg sheet under hard orientation loading was performed at strain rates of 1×10^(-5) and 1×10^(-1) s^(-1) with grain sizes of 70 and 20µm.There were 1609 tension twins identified including adequate(51%)anomalous twins(Schmid factor m<0).Twin variant selection exhibited almost no grain size or strain rate effects.Most twin variants(74%)correlated well with the proposed normalized Schmid factor(mnor).The Luster-Morris parameter(m′)values failed to correlate with the twin transmission,while 96%of transmitted pairs exhibited large mnor or normalized m′(m′nor)values.Twin transmission occurred more frequently at lower grain boundary misorientation angles(10°-30°).The active anomalous twins correlated well with m of the prismatic slip.The present work provided a statistical perspective that,the mnor and m′nor can correlate the anomalous twinning rather than m and m′.The local condition also played a critical role in anomalous twinning behavior.展开更多
AIM:To compare the Ishihara test errors scores of colour vision deficiency(CVD)subjects when wearing four different types of red-tinted contact lenses(RCL)that differ in their transmittance as determined using a spect...AIM:To compare the Ishihara test errors scores of colour vision deficiency(CVD)subjects when wearing four different types of red-tinted contact lenses(RCL)that differ in their transmittance as determined using a spectrophotometer.METHODS:Six congenital CVD subjects volunteered to participate in this study.Ishihara plates were used to determine the colour vision errors made,whereas Farnsworth-Munsell 100 Hue test was conducted to determine the total error scores(TES)and type of CVD.Four types of RCL(Types A,B,C and D)were inserted in the non-dominant eye and tested in a randomised manner by a masked operator.Errors scores in Ishihara test were determined at baseline without any contact lens and after wearing the four different RCL.The subjects were then divided into two groups based on the mean TES.RESULTS:Repeated measures ANOVA with Greenhouse-Geisser corrections showed that there was a highly significant effect of RCL type on Ishihara error score[F(2.056,10.282)=30.214,P<0.001].Error scores with RCL Type B were significantly lower than errors made when no lens was worn,and with RCL Type C and Type D(all P<0.001).Error scores with RCL Type B were also lower than those made with RCL Type A,however,they were not significantly different.For subjects with TES values less than 180,RCL type B showed the largest improvement in Ishihara error score(50%)compared to the other three RCLs.RCL type A showed the best performance in TES value of more than 180,with an improvement of 80%in Ishihara score.RCL Type A has the lowest transmittance at the confusion wavelength(450-568 nm),followed by RCL Types B,D and C.CONCLUSION:This study shows that RCL can improve Ishihara error scores.RCL with lower transmission at 450-568 nm and 90%transmittance beyond 637 nm are the most effective.Lenses which could block more light between 550-580 nm are more effective for colour defectives with more severe colour defects.展开更多
While the deformation behavior of rare-earth magnesium alloys at high temperatures has been extensively studied,the deformation mechanisms under moderate-to-low temperatures and high strain rates remain insufficiently...While the deformation behavior of rare-earth magnesium alloys at high temperatures has been extensively studied,the deformation mechanisms under moderate-to-low temperatures and high strain rates remain insufficiently understood.To address this gap,hot compression tests were conducted on a Mg-11Gd-3Y-0.5Zr(wt.%)alloy over a temperature range of 150℃–450℃under strain rates of 10^(-3) s^(-1)(low strain rate(LSR))and 10 s^(-1)(high strain rate(HSR))to explore the strain rate-temperature coupling effects during hot deformation.The results revealed an anomalous increase in peak stress at 150℃–250℃as the strain rate decreased,attributed to the combined effects of nano-precipitates,dislocation cell structures,and serrated flow induced by dynamic strain aging.At higher temperatures,strain rate influences softening pathways:under HSR at 450℃,the effect of twinning shifts from strengthening to facilitating dynamic recrystallization(DRX),resulting in substantial grain refinement(-4 μm,81%area fraction at a strain of 0.6).In contrast,at LSR,softening is dominated by dynamic recovery at 350℃,with limited DRX(-4 μm grains,10%area fraction at a strain of 0.6)occurs at 400℃.These findings clarify the dual role of twinning and its interaction with rate-temperature conditions,providing valuable insights into optimizing the hot processing of rare-earth magnesium alloys.展开更多
Single crystal(SX)superalloys are required for full-operating-temperature mechanical properties.How-ever,the quest for intermediate temperature(IT)resistance often encounters a perplexing phenomenon:anomalous yielding...Single crystal(SX)superalloys are required for full-operating-temperature mechanical properties.How-ever,the quest for intermediate temperature(IT)resistance often encounters a perplexing phenomenon:anomalous yielding behavior coupled with an unexpected loss of ductility.This study delved into the tensile behavior of a[111]-oriented SX superalloy from room temperature(RT)to 1150℃,uncover-ing temperature-dependent tensile mechanisms where the interplay among phases and deferent de-fects governs plastic deformation.Desirable high strength-ductility properties were observed at IT,show-casing comparable strength with increased ductility.Microstructural evidences show that the primary strengthening effects stem from coupled interface boundary strengthening and anti-phase boundary(APB)strengthening,while the plasticity arises from planer defects transitioning from the stacking fault(SF)withinγphase at small strains,to superlattice SFs,ultimately to the erasure of superlattice SFs,leaving cutting dislocation pairs inγʹphase.Energy analysis of APB and SF,along with adherence to Schmid laws,reinforce the plausibility of such intricate defect interactions.The strength-ductility balance can be ascribed to the collective effect of preferentially generated dislocations and prompt formation of SF.This strategy of sequential defects’competition provides a new route for solving the strength-ductility trade-offof alloys.展开更多
文摘Making use of the temperature data from 53 stations in Liaoning Province in April from 1961 to 2010 and the data of 500 hPa height field and sea surface temperature issued by National Climate Center,the characteristics of temperature,sea surface temperature(SST) and 500 hPa height field in April in 2010 were analyzed.The results showed that the anomalously lower temperature in April in 2010 was mainly caused by the anomalous Arctic Oscillation(AO),so as to provide scientific basis for short-term climate prediction.
基金supported by the National Natural ScienceFoundation (Grant No. 40872076)
文摘High-quality reservoirs occur in the middle-shallow horizons of the northern Songliao Basin. The distribution and genesis of their anomalously high porosity zones were studied using measured porosities, examination of ordinary thin sections and blue epoxy resin-impregnated thin sections and by SEM. The results show that there are three anomalously high porosity zones at the depth of 450-900 m, 1,300-1,900 m, 2,050-2,350 m respectively, named zone i, zone ii and zone iii from top to bottom. Horizontally, zone i and zone ii are distributed all over the basin except in the Southeastern Uplift, while zone iii is only distributed in the Central Depression. Zone i was formed by meteoric water leaching as well as organic acid dissolution. Zones ii and iii were dominantly formed by organic acid dissolution. Additionally, clay mineral transformation generating H＋ and hydrocarbon emplacement retarding the cementation of sandstones are also important for the formation of zones ii and iii.
文摘The description of experimentally observed phenomenon of abnormally high electrical conductivity—'superconductivity' (SC) at the room and higher temperatures is represented. The effect was observed in metallic monospirals of small radius curvature with high density and regular distribution of dislocations. Transition into state of SC has been observed experimentally in the range from –50 up to 3000°C at the density of transmitting current up to 2·109 A/cm2. The experimental data confirming the watched phenomenon are represented. The explanations of this phenomenon are being proposed in the framework of the dislocation model.
文摘In the present letters we study the propagation of smooth pulses in anomalously dispersive media. We prove that non-analytical but smooth points in a pulse still propagate with the vacuum speed of light, c. It gives an upper limit for signal velocity as well as the non-continuous points of the envelop of a pulse or its derivatives of arbitrary order do.
基金supported by the National Natural Science Foundation of China (Grant Nos.12274313 and 62375234)the Gusu Leading Talent Plan for Scientific and Technological Innovation and Entrepreneurship (Grant No.ZXL2024400)。
文摘Optical phase-gradient metasurfaces have garnered significant attention for enabling flexible light manipulation,with applications across diverse domains.In this work,we will demonstrate that the metasurfaces with phase gradient modulation can be used to achieve illusion optics,featuring the advantages of simple geometric structure and feasible implementation compared with the well-known transformation optics method.The underlying mechanism is the anomalous diffraction law caused by the phase gradient,which provides a theoretical basis for freely manipulating the propagation path of light.By considering a specific example,we will demonstrate that the phase gradient can transform spatial coordinates in real space into illusion space,thereby converting a plane in real space into a curved surface structure in illusion space to achieve the illusion effect.This approach provides a viable alternative to transformation optics for designing illusion devices.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403503,2022YFA1602802,2023YFA1607400,and 2024YFA1613200)Beijing Natural Science Foundation(Grant No.JQ23022)supported by the Synergetic Extreme Condition User Facility and the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302600)。
文摘Fe_(3)Sn_(2),a ferromagnetic metal with a kagome lattice,serves as an ideal platform for exploring topological electronic states and Berry curvature due to its unique band structure.However,systematic reports on the transport properties of Fe_(3)Sn_(2)nanosheets remain scarce.We present temperature-dependent transport property measurements of Fe_(3)Sn_(2)nanosheets synthesized via chemical vapor deposition on Si/SiO_(2)substrates.The samples exhibit a robust anomalous Hall effect from 40 K to 300 K,along with a magnetoresistance sign reversal at 40 K at high magnetic fields,indicating a spin reorientation from in-plane to out-of-plane.Notably,a sharp crossover in the dominant transport contribution from electrons to holes near 200 K is observed,accompanied by distinct anomalous Hall behaviors in the two regimes,indicating a temperature-induced Lifshitz transition within the multi-band system.This divergence is potentially linked to a topological reconstruction of the Fermi surface across the transition.Our findings highlight the tunability of topological transport in two-dimensional kagome magnets and provide new insights into the interplay between band topology,dimensionality and magnetic order.
基金Project supported by the National Natural Science Foundation of China(Grant No.12204347)National Key Research and Development Program of China(Grant No.2022YFA1402600)the Fund from Beijing National Laboratory for Condensed Matter Physics(Grant No.2023BNLCMPKF011)。
文摘Kagome magnets are of growing interest due to their topological electronic structures and unconventional magnetic behavior.Here,we report on the anomalous Hall effect(AHE)in the kagome ferromagnet MgMn_(6)Sn_(6),which has a Curie temperature of~290 K and an in-plane easy magnetization axis.Magnetotransport measurements show a positive magnetoresistance(MR)below 50 K,which becomes negative at higher temperatures.An intrinsic anomalous Hall conductivity of 114 S·cm^(-1)is observed in MgMn_(6)Sn_(6) single crystals,consistent with ab initio calculations.Moreover,theoretical predictions indicate that shifting the Fermi level(EF)upward by~70 meV could enhance the AHE to~528 S·cm^(-1).These results position MgMn_(6)Sn_(6) as a promising and tunable platform for exploring topological magnetism and related electronic phenomena.
文摘This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the increase of light amplitude;(Ⅳ)Formalism for light-induced anomalous Hall effects.
基金supported by the National Natural Science Foundation of China(Grant Nos.62525406,T2394473,624B2070,and 62274085)the National Key Research and Development Program of China(Grant No.2022YFA1402404)the Innovation Program for Quantum Science and Technology of China(Grant No.2024ZD0301300)。
文摘We report on the growth of CoFe_(2)O_(4)/Pt heterostructure and their magnetotransport properties.The magnetoresistance under high magnetic fields exhibits a sign change when the temperature increases from 5 K to 10 K.The anomalous Hall resistance decreases as the temperature increases.Furthermore,angle-dependent magnetoresistance indicates that the observed magnetotransport behaviors originate from the competition between the spin Hall magnetoresistance and magnetic proximity effect.
基金supported by the National Natural Science Foundation of China[grant numbers U2142207 and U2342205]the National Key R&D Program of China[grant number 2024YFC3013100]China Meteorological Administration(CMA)Youth Innovation Team[CMA2024QN06].
文摘Since the 21st century,the Huang–Huai–Hai River Basin(HHHRB)in China has experienced increased frequency and severity of drought–flood abrupt alternation(DFAA)events during early summer,characterized by droughts in June followed by floods in July.The 2024 event was the most severe since 1981.This study demonstrates that such compound extreme events are closely linked to anomalous subseasonal evolution of large-scale atmospheric circulation.During the drought phase,the East Asian subtropical westerly jet(EAJ)shifts southward,and the western Pacific subtropical high(WPSH)exhibits anomalous strengthening with its western ridge line displaced southward.The flood phase is characterized by acceleration of the EAJ,westward extension of the WPSH,and enhanced southwestern moisture transport from the western Pacific.Beyond these typical features,the 2024 early summer circulation exhibited unique characteristics:Anomalous northeastward intensification of the WPSH facilitated merged moisture influx from both the Indian Ocean and the western Pacific along the southeast pathway into the HHHRB in July,resulting in the highest net moisture inflow at the southern boundary of the HHHRB since 1981.The synergistic effects of multiple factors primarily explain the exceptionally intense DFAA event in 2024.
基金supported by the National Natural Science Foundation of China(12273008,12025303,12403046)the National SKA Program of China(2022SKA0130104)+3 种基金the Natural Science and Technology Foundation of Guizhou Province(QiankehejichuMS[2025]266,[2023]024,ZK[2022]304)the Foundation of Guizhou Provincial Education Department(KY(2020)003)the Academic New Seedling Fund Project of Guizhou Normal University([2022]B18)the Major Science and Technology Program of Xinjiang Uygur Autonomous Region(2022A03013-4).
文摘The emission of anomalous X-ray pulsars(AXPs)and soft gamma-ray repeaters(SGRs)is believed to be powered by the dissipation of their strong magnetic fields,which coined the name“magnetar”.By combining timing and energy observational results,the magnetar model can be easily appreciated.From a timing perspective,the magnetic field strengths of AXPs and SGRs,which are calculated under the assumption of dipole radiation,are extremely strong.From an energy perspective,the X-ray/soft gamma-ray luminosities of AXPs and SGRs are larger than their rotational energy loss rates(i.e.,L_(x>E_(rot)).It is thus reasonable to assume that the high-energy radiation comes from magnetic energy decay,and the magnetar model has been extensively discussed(or accepted).However,we argue that:(ⅰ)Calculating magnetic fields by assuming that rotational energy loss is dominated by dipole radiation(i.e.,E_(rot)■E_(μ))may be controversial,and we suggest that the energies carried by outflowing particles should also be considered.(ⅱ)The fact that X-ray luminosity is greater than the rotational energy loss rate does not necessarily mean that the emission energy comes from the magnetic field decaying,which requires further observational testing.Furthermore,some observational facts conflict with the“magnetar”model,such as observations of anti-magnetars,high magnetic field pulsars,and radio and X-ray observations of AXPs/SGRs.Therefore,we propose a crusted strange star model as an alternative,which can explain many more observational facts of AXPs/SGRs.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1408104,2021YFA1202901,and 2022YFA1204001)the National Natural Science Foundation of China(Grant Nos.92365203,U24A6002,52302180,and U21A2086)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20243011)the Hebei Natural Science Foundation No.E2023203002).
文摘Berry curvature describes the intrinsic geometric property of electronic band structure,crucial for governing emergent transport phenomena.As a typical Berry-curvature-related property,the anomalous Nernst effect probes local Berry curvature near the Fermi surface,whereas the anomalous Hall effect integrates contributions across all occupied states.Thus,the anomalous Nernst effect is a superior probe for detecting subtle evolution of Berry curvature near the Fermi level;however,their relation remains elusive.Here,we demonstrate giant anomalous Nernst angles induced by Berry curvature in layered itinerant ferromagnets Fe_(3)GaTe_(2)and Fe_(5)GeTe_(2).Their maximum values(≈0.33 for Fe_(3)GaTe_(2)and≈0.41 for Fe_(5)GeTe_(2))are one order of magnitude larger than those of traditional ferromagnets(θ_(AN)^(max)<0.02).Scaling analysis of anomalous Hall effect in these two systems further suggests these giant angles originate from intrinsic Berry curvature.These findings indicate Berrycurvature-dominated regimes,and establish these materials for high-performance spin-caloritronic devices.
基金supported by the National Natural Science Foundation of China(Grant No.12274117)the Natural Science Foundation of Henan(Grant No.242300421214)+4 种基金the Program for Innovative Research Team(in Science and Technology)in the University of Henan Province(Grant No.24IRTSTHN025)the Open Fund of Guangdong Provincial Key Laboratory of Nanophotonic Manipulation(No.202502)Guangdong S&T Program(No.2023B1212010008)the High-Performance Computing Center of Henan Normal Universitysupported by the U.S.DOE,Office of Science(Grant No.DE-FG02-05ER46237)。
文摘Altermagnetism,a recently identified class of collinear magnetism,combines key features of antiferromagnets and ferromagnets.Despite having zero net magnetization,altermagnetic materials exhibit anomalous transport effects,including the anomalous Hall,Nernst,and thermal Hall effects,as well as magneto-optical Kerr and Faraday effects.These phenomena,previously thought unique to ferromagnets,are dictated by symmetry,as confirmed by density functional theory(DFT)calculations.However,an effective model-based approach to verify these symmetry constraints remains unavailable.In this Letter,we construct a k·ρ model for d-wave altermagnets CuX_(2)(X=F,Cl)using spin space group representations and apply it to calculate the anomalous Hall effect.The symmetry-imposed transport properties predicted by the model are in agreement with the DFT results,providing a foundation for further investigation into symmetry-restricted transport phenomena in altermagnetic materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.12274313,62275184,and 62411540033)Collaborative Innovation Center of Suzhou Nano Science and Technology,Suzhou Basic Research Project(Grant No.SJC2023003)+1 种基金the Gusu Leading Talent Plan for Scientific and Technological Innovation and Entrepreneurship(Grant No.ZXL2024400)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Perfect anomalous reflections have been demonstrated in optical phase gradient metasurfaces(PGMs),but they suffer from single-frequency(narrow-band)response due to the intrinsic limitation of natural geometric periodicity.Here,we provide both numerical and analytical evidence that a depth gradient metasurface can achieve discrete ultra-broadband perfect anomalous reflection in the microwave range in the absence of geometric periodicity.Remarkably,by adjusting the operating frequency of the incident wave,the same effect can be steadily obtained via a physically equivalent phase periodicity in the PGM.Based on this mechanism,a perfect retroreflector with a broadband response ranging from 1 GHz to 40 GHz is realized.Our work has promising applications in communication,source tracking,and military satellites.
基金Supported by the 1.3.5 Project of West China Hospital of Sichuan University(No.2023HXFH043)Sichuan Natural Science Foundation(No.24NSFSC1718).
文摘Dear Editor,We describe a case diagnosed with exudative perifoveal vascular anomalous complex(ePVAC)successfully treated with focal laser photocoagulation(577 nm),achieving a favorable prognosis with best-corrected visual acuity(BCVA)of 20/20.Additionally,we discussed the identification of a possible early-onset non-ePVAC.The ePVAC is characterized as an isolated,aneurysmal abnormity near the macula and usually accompanied by cystic macular edema(ME)[1-2].
基金supported by the Shenzhen Science and Technology Program(Nos.JCYJ20220531095217039,RCBS20210609103202012)the National Natural Science Foundation of China(Nos.52101135,52222112,52101151 and 52301139)the Hong Kong Research Grant Council(RGC)(No.11208823).
文摘Chemically complex intermetallic alloys(CCIMAs)have emerged as promising materials tor achieving ex-ceptional softening resistance at elevated temperatures,owing to their unique superlattice structures and elemental synergism.However,the lack of experimental endeavors and understanding regarding their temperature-dependent mechanical behaviors hinders their advancement for high-temperature applica-tions.Here,we conducted a systematic investigation on the mechanical properties and associated defor-mation mechanisms of an L12-type Co-rich CCIMA using transmission electron microscopy.The Co-rich CCIMA exhibits superior strength across a wide temperature range of 700-900℃,with an anomalous peak yield strength(YS)of~1.0 GPa at 700℃,which surpasses most previously reported L12-type inter-metallic alloys.This superior softening resistance can be primarily attributed to a combination of cross-slip hardening and segregation-assisted hardening.Specifically,massive Kear-Wilsdorf(K-W)locks formed by multiple cube cross-slips of screw dislocations prevail at 700-900℃,providing strong barriers for dis-location movements and enhancing the yield strength(YS)accordingly.More interestingly,we revealed a segregation-assisted formation of superlattice stacking faults and nanotwins at the peak yield tempera-ture(700℃).The interlocking of these substructures and the associated element dragging effect further impeded the propagation of dislocations,contributing to the observed yield anomaly.This work provides in-depth insight into the high-temperature performance and deformation behaviors of CCIMAs,which paves the way for the future development of novel heat-resistant structural alloys.
基金supported by the National Natural Science Foundation of China(Nos.52171125,52071178)。
文摘A statistical analysis of the twinning behavior in a basal-textured Mg sheet under hard orientation loading was performed at strain rates of 1×10^(-5) and 1×10^(-1) s^(-1) with grain sizes of 70 and 20µm.There were 1609 tension twins identified including adequate(51%)anomalous twins(Schmid factor m<0).Twin variant selection exhibited almost no grain size or strain rate effects.Most twin variants(74%)correlated well with the proposed normalized Schmid factor(mnor).The Luster-Morris parameter(m′)values failed to correlate with the twin transmission,while 96%of transmitted pairs exhibited large mnor or normalized m′(m′nor)values.Twin transmission occurred more frequently at lower grain boundary misorientation angles(10°-30°).The active anomalous twins correlated well with m of the prismatic slip.The present work provided a statistical perspective that,the mnor and m′nor can correlate the anomalous twinning rather than m and m′.The local condition also played a critical role in anomalous twinning behavior.
文摘AIM:To compare the Ishihara test errors scores of colour vision deficiency(CVD)subjects when wearing four different types of red-tinted contact lenses(RCL)that differ in their transmittance as determined using a spectrophotometer.METHODS:Six congenital CVD subjects volunteered to participate in this study.Ishihara plates were used to determine the colour vision errors made,whereas Farnsworth-Munsell 100 Hue test was conducted to determine the total error scores(TES)and type of CVD.Four types of RCL(Types A,B,C and D)were inserted in the non-dominant eye and tested in a randomised manner by a masked operator.Errors scores in Ishihara test were determined at baseline without any contact lens and after wearing the four different RCL.The subjects were then divided into two groups based on the mean TES.RESULTS:Repeated measures ANOVA with Greenhouse-Geisser corrections showed that there was a highly significant effect of RCL type on Ishihara error score[F(2.056,10.282)=30.214,P<0.001].Error scores with RCL Type B were significantly lower than errors made when no lens was worn,and with RCL Type C and Type D(all P<0.001).Error scores with RCL Type B were also lower than those made with RCL Type A,however,they were not significantly different.For subjects with TES values less than 180,RCL type B showed the largest improvement in Ishihara error score(50%)compared to the other three RCLs.RCL type A showed the best performance in TES value of more than 180,with an improvement of 80%in Ishihara score.RCL Type A has the lowest transmittance at the confusion wavelength(450-568 nm),followed by RCL Types B,D and C.CONCLUSION:This study shows that RCL can improve Ishihara error scores.RCL with lower transmission at 450-568 nm and 90%transmittance beyond 637 nm are the most effective.Lenses which could block more light between 550-580 nm are more effective for colour defectives with more severe colour defects.
基金financially supported by the National Natural Science Foundation of China (grants 52301146 and 52275308)the Fundamental Research Funds for the Central Universities (grant 2023JG007)China Postdoctoral Science Foundation (grant 8206300226)。
文摘While the deformation behavior of rare-earth magnesium alloys at high temperatures has been extensively studied,the deformation mechanisms under moderate-to-low temperatures and high strain rates remain insufficiently understood.To address this gap,hot compression tests were conducted on a Mg-11Gd-3Y-0.5Zr(wt.%)alloy over a temperature range of 150℃–450℃under strain rates of 10^(-3) s^(-1)(low strain rate(LSR))and 10 s^(-1)(high strain rate(HSR))to explore the strain rate-temperature coupling effects during hot deformation.The results revealed an anomalous increase in peak stress at 150℃–250℃as the strain rate decreased,attributed to the combined effects of nano-precipitates,dislocation cell structures,and serrated flow induced by dynamic strain aging.At higher temperatures,strain rate influences softening pathways:under HSR at 450℃,the effect of twinning shifts from strengthening to facilitating dynamic recrystallization(DRX),resulting in substantial grain refinement(-4 μm,81%area fraction at a strain of 0.6).In contrast,at LSR,softening is dominated by dynamic recovery at 350℃,with limited DRX(-4 μm grains,10%area fraction at a strain of 0.6)occurs at 400℃.These findings clarify the dual role of twinning and its interaction with rate-temperature conditions,providing valuable insights into optimizing the hot processing of rare-earth magnesium alloys.
基金sponsored by the National Natural Science Foundations of China(Nos.52101116,52301126,and 92360302)the Science Center for Gas Turbine Project(Nos.P2022-A-I-001-001 and P2022-A-Ⅰ-002-002)+2 种基金the National Science and Technology Major Project(No.2019-Ⅵ-0016-0131)the Beijing Nova Program(No.20230484318)the Key R&D Program of Zhejiang(No.2024SSYS0076).
文摘Single crystal(SX)superalloys are required for full-operating-temperature mechanical properties.How-ever,the quest for intermediate temperature(IT)resistance often encounters a perplexing phenomenon:anomalous yielding behavior coupled with an unexpected loss of ductility.This study delved into the tensile behavior of a[111]-oriented SX superalloy from room temperature(RT)to 1150℃,uncover-ing temperature-dependent tensile mechanisms where the interplay among phases and deferent de-fects governs plastic deformation.Desirable high strength-ductility properties were observed at IT,show-casing comparable strength with increased ductility.Microstructural evidences show that the primary strengthening effects stem from coupled interface boundary strengthening and anti-phase boundary(APB)strengthening,while the plasticity arises from planer defects transitioning from the stacking fault(SF)withinγphase at small strains,to superlattice SFs,ultimately to the erasure of superlattice SFs,leaving cutting dislocation pairs inγʹphase.Energy analysis of APB and SF,along with adherence to Schmid laws,reinforce the plausibility of such intricate defect interactions.The strength-ductility balance can be ascribed to the collective effect of preferentially generated dislocations and prompt formation of SF.This strategy of sequential defects’competition provides a new route for solving the strength-ductility trade-offof alloys.
