We present a comprehensive investigation into the physical properties of intermetallic ErPd_(2)Si_(2),a compound renowned for its intriguing magnetic and electronic characteristics.We confirm the tetragonal crystal st...We present a comprehensive investigation into the physical properties of intermetallic ErPd_(2)Si_(2),a compound renowned for its intriguing magnetic and electronic characteristics.We confirm the tetragonal crystal structure of ErPd_(2)Si_(2)within the I4/mmm space group.Notably,we observed anisotropic thermal expansion,with the lattice constant a expanding and c contracting between 15 and300 K.This behaviour is attributed to lattice vibrations and electronic contributions.Heat capacity measurements revealed three distinct temperature regimes:T_(1)~3.0 K,T_(N)~4.20 K,and T_(2)~15.31 K.These correspond to thedisappearance of spin-density waves,the onset of an incommensurate antiferromagnetic(AFM)structure,and the crystal-field splitting and/or the presence of short-range spin fluctuations,respectively.Remarkably,the AFM phase transition anomaly was observed exclusively in lowfield magnetization data(120 Oe)at T_(N).A high magnetic field(B=3 T)effectively suppressed this anomaly,likely due to spin-flop and spin-flip transitions.Furthermore,the extracted effective paramagnetic(PM)moments closely matched the expected theoretical value,suggesting a dominant magnetic contribution from localized 4f spins of Er.Additionally,significant differences in resistance(R)values at low temperatures under applied B indicated a magnetoresistance(MR)effect with a minimum value of-4.36%.Notably,the measured MR effect exhibited anisotropic behavior,where changes in the strength or direction of the applied B induced variations in the MR effect.A twofold symmetry of R was discerned at 3 and9 T,originating from the orientation of spin moments relative to the applied B.Intriguingly,above T_(N),shortrange spin fluctuations also displayed a preferred orientation along the c-axis due to single-ion anisotropy.Moreover,the R demonstrated a clear B dependence below30 K.The magnetic-field point where R transitions from linear B dependence to a stable state increased with temperature:~3 T(at 2 K),~4.5 T(at 4 K),and~6 T(at 10 K).Our study sheds light on the magnetic and electronic properties of ErPd_(2)Si_(2),offering valuable insights for potential applications in spintronics and quantum technologies.展开更多
Type-II Dirac semimetal PtTe2is a promising candidate for various electronic device applications due to its high carrier mobility,high conductivity,and air stability.In this work,we report on the growth of large-scale...Type-II Dirac semimetal PtTe2is a promising candidate for various electronic device applications due to its high carrier mobility,high conductivity,and air stability.In this work,we report on the growth of large-scale PtTe_(2)films by the pulsed laser deposition(PLD)and the comparison of the magnetotransport properties with the PtTe2films grown by the chemical vapor deposition(CVD).The low-temperature Hall curves of the PLD-grown films exhibit a linear behavior,in contrast with the nonlinear characteristic of the Hall behavior observed in CVD-grown films,in which a defect gradient is introduced.Meanwhile,both PtTe2films show weak antilocalization at low temperatures,which is attributed to the strong spin–orbit coupling.展开更多
Simulations are performed on clusters of finite size to study the effects of size and current-path structure on magnetotransport in spatially-confined samples. Magnetotransport networks are established and calculated ...Simulations are performed on clusters of finite size to study the effects of size and current-path structure on magnetotransport in spatially-confined samples. Magnetotransport networks are established and calculated based on fractal structures including Koch curves and percolation backbones extracted from regular lattices. The structure pattern of clusters is shown to play an important role in the magnetotransport behaviours by affecting the magnetore- sistance fluctuations due to spin disorder in the systems of small size, which suggests the possibility of controlling the magnetotransport by the design of current-path configurations.展开更多
We report the magnetoresistance（MR）, de Haas-van Alphen（dHvA） effect and Hall effect measurements on a single crystal of TiSi, which is predicted to be a nodal line semimetal. With application of a magnetic field,...We report the magnetoresistance（MR）, de Haas-van Alphen（dHvA） effect and Hall effect measurements on a single crystal of TiSi, which is predicted to be a nodal line semimetal. With application of a magnetic field, a metal-to-insulator-like transition in ρ（T） and a nonsaturating MR are observed at low temperatures. The dHvA oscillations reveal a small Fermi-surface pocket with a nontrivial Berry phase. The analysis of the nonlinear Hall resistivity shows that TiSi is a multiband system with low carrier densities and high mobilities. All these results unambiguously prove the existence of Dirac fermions in TiSi.展开更多
Magnetotransport measurements are carried out on the A1GaN/A1N/GaN in an SiC heterostructure, which demon- strates the existence of the high-quality two-dimensional electron gas （2DGE） at the A1N/GaN interface. Whil...Magnetotransport measurements are carried out on the A1GaN/A1N/GaN in an SiC heterostructure, which demon- strates the existence of the high-quality two-dimensional electron gas （2DGE） at the A1N/GaN interface. While the carrier concentration reaches 1.32×10^13 cm^-2 and stays relatively unchanged with the decreasing temperature, the mobility of the 2DEG increases to 1.21 × 10^4 cm2/（V.s） at 2 K. The Shubnikov-de Haas （SdH） oscillations are observed in a magnetic field as low as 2.5 T at 2 K. By the measurements and the analyses of the temperature-dependent SdH oscillations, the effective mass of the 2DEC is determined. The ratio of the transport lifetime to the quantum scattering time is 9 in our sample, indicating that small-angle scattering is predominant.展开更多
We propose in this paper that a dual waveguide coupled by a finite barrier be able to serve as an energy filter under a perpendicular magnetic field. In the waveguide direction, the conductance exhibits a periodic squ...We propose in this paper that a dual waveguide coupled by a finite barrier be able to serve as an energy filter under a perpendicular magnetic field. In the waveguide direction, the conductance exhibits a periodic square-wave pattern in which the miniband is controlled by the magnetic and potential modulation. The electrons with energies in the miniband can completely transfer along one waveguide while the other electrons undergo filtration. Compared with the coupled waveguide without magnetic modulation, the structure under magnetic field is found to be a good directional coupler. By adjusting the potential barrier and magnetic field, the electrons input from one port of waveguide can transfer to any other ports.展开更多
In this paper,we investigate the effects of lattice strain on the electrical and magnetotransport properties of La0.7Sr0.3MnO3(LSMO)films by changing film thickness and substrate.For electrical properties,a resistivit...In this paper,we investigate the effects of lattice strain on the electrical and magnetotransport properties of La0.7Sr0.3MnO3(LSMO)films by changing film thickness and substrate.For electrical properties,a resistivity upturn emerges in LSMO films,i.e.,LSMO/STO and LSMO/LSAT with small lattice strain at a low temperature,which originates from the weak localization effect.Increasing film thickness weakens the weak localization effect,resulting in the disappearance of resistivity upturn.While in LSMO films with a large lattice strain(i.e.,LSMO/LAO),an unexpected semiconductor behavior is observed due to the linear defects.For magnetotransport properties,an anomalous in-plane magnetoresistance peak(pMR)occurs at low temperatures in LSMO films with small lattice strain,which is caused by two-dimensional electron gas(2DEG).Increasing film thickness suppresses the 2DEG,which weakens the pMR.Besides,it is found that the film orientation has no influence on the formation of 2DEG.While in LSMO/LAO films,the 2DEG cannot form due to the existence of linear defects.This work can provide an efficient way to regulate the film transport properties.展开更多
The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ io...The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2+ and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2+, Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2+ and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2+ and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.展开更多
Layered rare earth magnets make a prolific source of unconventional quantum phases and functional properties.Recently,a class of Zintl materials EuA2X2has emerged as holding promise for ideal Weyl and axion physics.Th...Layered rare earth magnets make a prolific source of unconventional quantum phases and functional properties.Recently,a class of Zintl materials EuA2X2has emerged as holding promise for ideal Weyl and axion physics.The question is whether the magnetic structure,strongly coupled to the topology,can be controlled in such mate rials via a minimal yet selective modification of their chemical composition.Here,we report qualitative changes in the magnetic structure due to charge imbalance.Such imbalance is probed by replacement of Eu with Gd.The two elements form isoelectronic 4f7cations but contribute to different numbers of electrons.A synthetic route to epitaxial films of GdAl_(2)Ge_(2)on Ge,employing a selfsacrificial template,is proposed.The ato mic and magnetic structures of the films,as well as their electron transport properties were studied by a combination of techniques.It is established that the change in the magnetic structure caused by the cationic replacement influences the magnetotransport properties of the films.The results suggest that the charge imbalance in Zintl compounds may provide an instrument to open new routes to functional layered materials with potential applications in spintronics.展开更多
The kagome lattice hosts unique electronic structure with Dirac fermions,van Hove singularities,and flat bands,which has been subjected to intensive study in recent years.We report herein the observation of significan...The kagome lattice hosts unique electronic structure with Dirac fermions,van Hove singularities,and flat bands,which has been subjected to intensive study in recent years.We report herein the observation of significantly enhanced magnetism including a very large coercive magnetic field up to 4.7 T,optimized magnetic energy product with the maximum value of 45 kJ/m^(3),and an increased magnetic ordering temperature reaching 113 K in Mn-substituted kagome metal TbV_(6)Sn_(6),namely,TbV_(5)MnSn_(6).Besides,both topological Hall-like and anomalous Hall effects are detected,with the latter being primarily dominated by intrinsic Berry curvature as indicated by our data analysis and theoretical calculations.Our work establishes an effective route for engineering the physical properties of kagome magnets.The results also provide valuable insights into the interplay between magnetism and topological states of the kagome lattice.展开更多
With a large number of researches being conducted on two?dimen?sional(2D)materials,their unique properties in optics,electrics,mechanics,and magnetics have attracted increasing attention.Accordingly,the idea of combin...With a large number of researches being conducted on two?dimen?sional(2D)materials,their unique properties in optics,electrics,mechanics,and magnetics have attracted increasing attention.Accordingly,the idea of combining distinct functional 2D materials into heterostructures naturally emerged that pro?vides unprecedented platforms for exploring new physics that are not accessible in a single 2D material or 3D heterostructures.Along with the rapid development of controllable,scalable,and programmed synthesis techniques of high?quality 2D heterostructures,various heterostructure devices with extraordinary performance have been designed and fabricated,including tunneling transistors,photodetectors,and spintronic devices.In this review,we present a summary of the latest progresses in fabrications,properties,and applications of di erent types of 2D heterostruc?tures,followed by the discussions on present challenges and perspectives of further investigations.展开更多
Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped GaSb grown by the liquid encapsuled Czochralski technique are carried out as functions of temperature （35-350 K） and magnetic field （0...Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped GaSb grown by the liquid encapsuled Czochralski technique are carried out as functions of temperature （35-350 K） and magnetic field （0-1.35 T）. The power law model is used to explain the temperature-dependent resistivity. The magnetic-field-dependent data are analysed using the quantitative mobility spectrum analysis technique. The effect of individual band parameters （nL, nr, μL, μr, p and μp） on both the electron and magneto transports have been discussed. The EL - Er energy separation between the L and conduction band edges is also derived.展开更多
Base optimum thickness is determined for a front illuminated bifacial silicon solar cell n<sup>+</sup>-p<span style="font-size:10px;">-</span>p<sup>+</sup> under magnetic ...Base optimum thickness is determined for a front illuminated bifacial silicon solar cell n<sup>+</sup>-p<span style="font-size:10px;">-</span>p<sup>+</sup> under magnetic field. From the magneto transport equation relative to excess minority carriers in the base, with specific boundary conditions, the photocurrent is obtained. From this result the expressions of the carrier’s recombination velocity at the back surface are deducted. These new expressions of recombination velocity are plotted according to the depth of the base, to deduce the optimum thickness, which will allow the production, of a high short-circuit photocurrent. Calibration relationships of optimum thickness versus magnetic field were presented according to study ranges. It is found that, applied magnetic field imposes a weak thickness material for solar cell manufacturing leading to high short-circuit current.展开更多
采用磁控溅射法在硅基片上制备了Co原子分数为13.0%的Co-C纳米复合薄膜.在真空条件下,对薄膜进行退火处理,退火温度从473K逐步提高至773K,保温时间30min.形貌观察表明,未经退火处理的薄膜中,Co颗粒均匀分布在非晶C基体中,Co颗粒尺寸为1....采用磁控溅射法在硅基片上制备了Co原子分数为13.0%的Co-C纳米复合薄膜.在真空条件下,对薄膜进行退火处理,退火温度从473K逐步提高至773K,保温时间30min.形貌观察表明,未经退火处理的薄膜中,Co颗粒均匀分布在非晶C基体中,Co颗粒尺寸为1.5-3.0nm;673K退火后,Co颗粒尺寸增大.磁性能测试表明,未经退火处理的薄膜磁性较弱,随着退火温度升高,薄膜的磁化强度和矫顽力均明显增大;当退火温度增加至673—773K时,薄膜呈现出低温铁磁性、室温超顺磁性的典型颗粒体系磁性特征.磁输运特性研究表明,未经退火处理的薄膜在温度为4.2K,磁场为3980kA/m时表现出1.33%的负磁电阻,随着退火温度升高,样品磁电阻值下降;电阻与温度关系在4.2—60K范围内符合lnR-T^(-1/4)线性关系,磁输运遵循变程跳跃(variable range hopping)传导机制.展开更多
基金supported by the Science and Technology Development Fund,Macao SAR,China(File Nos.0090/2021/A2 and 0104/2024/AFJ)University of Macao(MYRG-GRG2024-00158-IAPME)+3 种基金the support from the National Natural Science Foundation of China(No.52275467)the support from the National Natural Science Foundation of China(No.52271037)Shaanxi Provincial Natural Science Fundamental Research Program,China(No.2023-JC-ZD-23)the Fundamental Research Funds for the Central Universities of China(No.D5000240307)
文摘We present a comprehensive investigation into the physical properties of intermetallic ErPd_(2)Si_(2),a compound renowned for its intriguing magnetic and electronic characteristics.We confirm the tetragonal crystal structure of ErPd_(2)Si_(2)within the I4/mmm space group.Notably,we observed anisotropic thermal expansion,with the lattice constant a expanding and c contracting between 15 and300 K.This behaviour is attributed to lattice vibrations and electronic contributions.Heat capacity measurements revealed three distinct temperature regimes:T_(1)~3.0 K,T_(N)~4.20 K,and T_(2)~15.31 K.These correspond to thedisappearance of spin-density waves,the onset of an incommensurate antiferromagnetic(AFM)structure,and the crystal-field splitting and/or the presence of short-range spin fluctuations,respectively.Remarkably,the AFM phase transition anomaly was observed exclusively in lowfield magnetization data(120 Oe)at T_(N).A high magnetic field(B=3 T)effectively suppressed this anomaly,likely due to spin-flop and spin-flip transitions.Furthermore,the extracted effective paramagnetic(PM)moments closely matched the expected theoretical value,suggesting a dominant magnetic contribution from localized 4f spins of Er.Additionally,significant differences in resistance(R)values at low temperatures under applied B indicated a magnetoresistance(MR)effect with a minimum value of-4.36%.Notably,the measured MR effect exhibited anisotropic behavior,where changes in the strength or direction of the applied B induced variations in the MR effect.A twofold symmetry of R was discerned at 3 and9 T,originating from the orientation of spin moments relative to the applied B.Intriguingly,above T_(N),shortrange spin fluctuations also displayed a preferred orientation along the c-axis due to single-ion anisotropy.Moreover,the R demonstrated a clear B dependence below30 K.The magnetic-field point where R transitions from linear B dependence to a stable state increased with temperature:~3 T(at 2 K),~4.5 T(at 4 K),and~6 T(at 10 K).Our study sheds light on the magnetic and electronic properties of ErPd_(2)Si_(2),offering valuable insights for potential applications in spintronics and quantum technologies.
基金Project supported by the National Key R&D Program of China(Grant No.2022YFA1402404)the National Natural Science Foundation of China(Grant Nos.T2394473,624B2070,and 62274085)。
文摘Type-II Dirac semimetal PtTe2is a promising candidate for various electronic device applications due to its high carrier mobility,high conductivity,and air stability.In this work,we report on the growth of large-scale PtTe_(2)films by the pulsed laser deposition(PLD)and the comparison of the magnetotransport properties with the PtTe2films grown by the chemical vapor deposition(CVD).The low-temperature Hall curves of the PLD-grown films exhibit a linear behavior,in contrast with the nonlinear characteristic of the Hall behavior observed in CVD-grown films,in which a defect gradient is introduced.Meanwhile,both PtTe2films show weak antilocalization at low temperatures,which is attributed to the strong spin–orbit coupling.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10774107, 10874126 and 10804080)the Doctoral Program of High Education of China (Grant No 20060285003)
文摘Simulations are performed on clusters of finite size to study the effects of size and current-path structure on magnetotransport in spatially-confined samples. Magnetotransport networks are established and calculated based on fractal structures including Koch curves and percolation backbones extracted from regular lattices. The structure pattern of clusters is shown to play an important role in the magnetotransport behaviours by affecting the magnetore- sistance fluctuations due to spin disorder in the systems of small size, which suggests the possibility of controlling the magnetotransport by the design of current-path configurations.
基金Supported by the National Key Research Program of China under Grant Nos 2016YFA0401000 and 2016YFA0300604the National Basic Research Program of China under Grant No 2015CB921303+1 种基金the Strategic Priority Research Program(B)of Chinese Academy of Sciences under Grant No XDB07020100the National Natural Science Foundation of China under Grant No11874417
文摘We report the magnetoresistance（MR）, de Haas-van Alphen（dHvA） effect and Hall effect measurements on a single crystal of TiSi, which is predicted to be a nodal line semimetal. With application of a magnetic field, a metal-to-insulator-like transition in ρ（T） and a nonsaturating MR are observed at low temperatures. The dHvA oscillations reveal a small Fermi-surface pocket with a nontrivial Berry phase. The analysis of the nonlinear Hall resistivity shows that TiSi is a multiband system with low carrier densities and high mobilities. All these results unambiguously prove the existence of Dirac fermions in TiSi.
基金Project supported by the National Basic Research Program of China (Grant No.2011CB309606)
文摘Magnetotransport measurements are carried out on the A1GaN/A1N/GaN in an SiC heterostructure, which demon- strates the existence of the high-quality two-dimensional electron gas （2DGE） at the A1N/GaN interface. While the carrier concentration reaches 1.32×10^13 cm^-2 and stays relatively unchanged with the decreasing temperature, the mobility of the 2DEG increases to 1.21 × 10^4 cm2/（V.s） at 2 K. The Shubnikov-de Haas （SdH） oscillations are observed in a magnetic field as low as 2.5 T at 2 K. By the measurements and the analyses of the temperature-dependent SdH oscillations, the effective mass of the 2DEC is determined. The ratio of the transport lifetime to the quantum scattering time is 9 in our sample, indicating that small-angle scattering is predominant.
文摘We propose in this paper that a dual waveguide coupled by a finite barrier be able to serve as an energy filter under a perpendicular magnetic field. In the waveguide direction, the conductance exhibits a periodic square-wave pattern in which the miniband is controlled by the magnetic and potential modulation. The electrons with energies in the miniband can completely transfer along one waveguide while the other electrons undergo filtration. Compared with the coupled waveguide without magnetic modulation, the structure under magnetic field is found to be a good directional coupler. By adjusting the potential barrier and magnetic field, the electrons input from one port of waveguide can transfer to any other ports.
基金Project supported by the National Natural Science Foundation of China(Grant No.10974105)the Double-Hundred Talent Plan,Shandong Province,China(Grant No.WST2018006)+1 种基金the Recruitment Program of High-end Foreign Experts,China(Grant Nos.GDW20163500110 and GDW20173500154)the Top-notch Innovative Talent Program of Qingdao City,China(Grant No.13-CX-8).One of the authors(Yi-Qian Wang)was sponsored by the Taishan Scholar Program of Shandong Province,China,the Qingdao International Center for Semiconductor Photoelectric Nanomaterials,China,and Shandong Provincial University Key Laboratory of Optoelectrical Material Physics and Devices,China.
文摘In this paper,we investigate the effects of lattice strain on the electrical and magnetotransport properties of La0.7Sr0.3MnO3(LSMO)films by changing film thickness and substrate.For electrical properties,a resistivity upturn emerges in LSMO films,i.e.,LSMO/STO and LSMO/LSAT with small lattice strain at a low temperature,which originates from the weak localization effect.Increasing film thickness weakens the weak localization effect,resulting in the disappearance of resistivity upturn.While in LSMO films with a large lattice strain(i.e.,LSMO/LAO),an unexpected semiconductor behavior is observed due to the linear defects.For magnetotransport properties,an anomalous in-plane magnetoresistance peak(pMR)occurs at low temperatures in LSMO films with small lattice strain,which is caused by two-dimensional electron gas(2DEG).Increasing film thickness suppresses the 2DEG,which weakens the pMR.Besides,it is found that the film orientation has no influence on the formation of 2DEG.While in LSMO/LAO films,the 2DEG cannot form due to the existence of linear defects.This work can provide an efficient way to regulate the film transport properties.
基金Supported by the National Major Fundamental Research Program of China (Grant No G1998061412)the Foundation for Fostering Elitists of Beijing, China (Grant No 20071D1100500379)
文摘The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2+ and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2+, Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2+ and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2+ and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.
基金Project supported by NRC "Kurchatov Institute"the Russian Science Foundation (22-13-00004 (synthesis)),24-19-00038 (magnetism studies)and 20-79-10028 (electron transport studies)the President's scholarship for D.V.A.(SP 3111.2022.5)。
文摘Layered rare earth magnets make a prolific source of unconventional quantum phases and functional properties.Recently,a class of Zintl materials EuA2X2has emerged as holding promise for ideal Weyl and axion physics.The question is whether the magnetic structure,strongly coupled to the topology,can be controlled in such mate rials via a minimal yet selective modification of their chemical composition.Here,we report qualitative changes in the magnetic structure due to charge imbalance.Such imbalance is probed by replacement of Eu with Gd.The two elements form isoelectronic 4f7cations but contribute to different numbers of electrons.A synthetic route to epitaxial films of GdAl_(2)Ge_(2)on Ge,employing a selfsacrificial template,is proposed.The ato mic and magnetic structures of the films,as well as their electron transport properties were studied by a combination of techniques.It is established that the change in the magnetic structure caused by the cationic replacement influences the magnetotransport properties of the films.The results suggest that the charge imbalance in Zintl compounds may provide an instrument to open new routes to functional layered materials with potential applications in spintronics.
基金supported by the National Key R&D Program of China(Grant Nos.2024YFA1400066,2023YFA1406100,and 2024YFA1410300)the open research fund of Beijing National Laboratory for Condensed Matter Physics(Grant No.2023BNLCMPKF002)+2 种基金the National Natural Science Foundation of China(Grant No.12304217)Analytical Instrumentation Center(Grant No.SPST-AIC10112914)the Double First-Class Initiative Fund of ShanghaiTech University.
文摘The kagome lattice hosts unique electronic structure with Dirac fermions,van Hove singularities,and flat bands,which has been subjected to intensive study in recent years.We report herein the observation of significantly enhanced magnetism including a very large coercive magnetic field up to 4.7 T,optimized magnetic energy product with the maximum value of 45 kJ/m^(3),and an increased magnetic ordering temperature reaching 113 K in Mn-substituted kagome metal TbV_(6)Sn_(6),namely,TbV_(5)MnSn_(6).Besides,both topological Hall-like and anomalous Hall effects are detected,with the latter being primarily dominated by intrinsic Berry curvature as indicated by our data analysis and theoretical calculations.Our work establishes an effective route for engineering the physical properties of kagome magnets.The results also provide valuable insights into the interplay between magnetism and topological states of the kagome lattice.
基金supported by NSF of China(Grant No.61775241)partly by the Innovation-driven Project(Grant No.2017CX019)the funding support from the Australian Research Council(ARC Discovery Projects,DP180102976)
文摘With a large number of researches being conducted on two?dimen?sional(2D)materials,their unique properties in optics,electrics,mechanics,and magnetics have attracted increasing attention.Accordingly,the idea of combining distinct functional 2D materials into heterostructures naturally emerged that pro?vides unprecedented platforms for exploring new physics that are not accessible in a single 2D material or 3D heterostructures.Along with the rapid development of controllable,scalable,and programmed synthesis techniques of high?quality 2D heterostructures,various heterostructure devices with extraordinary performance have been designed and fabricated,including tunneling transistors,photodetectors,and spintronic devices.In this review,we present a summary of the latest progresses in fabrications,properties,and applications of di erent types of 2D heterostruc?tures,followed by the discussions on present challenges and perspectives of further investigations.
文摘Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped GaSb grown by the liquid encapsuled Czochralski technique are carried out as functions of temperature （35-350 K） and magnetic field （0-1.35 T）. The power law model is used to explain the temperature-dependent resistivity. The magnetic-field-dependent data are analysed using the quantitative mobility spectrum analysis technique. The effect of individual band parameters （nL, nr, μL, μr, p and μp） on both the electron and magneto transports have been discussed. The EL - Er energy separation between the L and conduction band edges is also derived.
文摘Base optimum thickness is determined for a front illuminated bifacial silicon solar cell n<sup>+</sup>-p<span style="font-size:10px;">-</span>p<sup>+</sup> under magnetic field. From the magneto transport equation relative to excess minority carriers in the base, with specific boundary conditions, the photocurrent is obtained. From this result the expressions of the carrier’s recombination velocity at the back surface are deducted. These new expressions of recombination velocity are plotted according to the depth of the base, to deduce the optimum thickness, which will allow the production, of a high short-circuit photocurrent. Calibration relationships of optimum thickness versus magnetic field were presented according to study ranges. It is found that, applied magnetic field imposes a weak thickness material for solar cell manufacturing leading to high short-circuit current.
基金National Natural Science Foundation of China(51041010)The Ph.D.Programs Foundation of Ministry of Education of China(20090002110007)the National Basic Research Program of China(2010CB934602)
文摘采用磁控溅射法在硅基片上制备了Co原子分数为13.0%的Co-C纳米复合薄膜.在真空条件下,对薄膜进行退火处理,退火温度从473K逐步提高至773K,保温时间30min.形貌观察表明,未经退火处理的薄膜中,Co颗粒均匀分布在非晶C基体中,Co颗粒尺寸为1.5-3.0nm;673K退火后,Co颗粒尺寸增大.磁性能测试表明,未经退火处理的薄膜磁性较弱,随着退火温度升高,薄膜的磁化强度和矫顽力均明显增大;当退火温度增加至673—773K时,薄膜呈现出低温铁磁性、室温超顺磁性的典型颗粒体系磁性特征.磁输运特性研究表明,未经退火处理的薄膜在温度为4.2K,磁场为3980kA/m时表现出1.33%的负磁电阻,随着退火温度升高,样品磁电阻值下降;电阻与温度关系在4.2—60K范围内符合lnR-T^(-1/4)线性关系,磁输运遵循变程跳跃(variable range hopping)传导机制.
