Electrochemically switched ion exchange(ESIX)is an effective technology for extracting high-valueadded ions from dilute solutions.This study focuses on Li^(+)extraction by employing a comprehensive model to analyze in...Electrochemically switched ion exchange(ESIX)is an effective technology for extracting high-valueadded ions from dilute solutions.This study focuses on Li^(+)extraction by employing a comprehensive model to analyze interaction between fluidic dynamics,electric field and ion transport.The model combines Butler-Volmer equation modified by electroactive site concentration,Nernst-Planck equation and Navier-Stokes equation.It is found that the chamber width affects solution phase resistance,thereby altering the pote ntial distribution and influencing the current distribution within the membrane.A narrow chamber increases current density in the solid phase of the membrane,enhancing Li^(+) extraction.The solution flow-field not only enhances convective transport but also increases the current density in the solid phase,promoting Li^(+) extraction.There is a synergistic effect between fluid-flow-field and electric-field for ion separation,which is only significant when the chamber width is greater than 2 mm.The synergistic mechanism differs from that in the capacitive deionization system.Therefore,the performance decline caused by a wide chamber can be compensated for by increasing the fluid-flow rate,utilizing the synergistic effect between the flu id-flow-field and electric-field to optimize the lithium extraction efficiency in the ESIX system.展开更多
The effects of electric-field treatment on the microstructure and deformation behavior of a nickel-base superalloy were summarized.The results show that the electric-field treatment increases the ductility of the supe...The effects of electric-field treatment on the microstructure and deformation behavior of a nickel-base superalloy were summarized.The results show that the electric-field treatment increases the ductility of the superalloy but has no evident influence on its static strength at both room and elevated temperatures,while,the strength increases but elongation changes weekly with the increasing tensile strain rate.It is found that the direction of microcrack propagation can be changed by the presence of the annealing twins during the tensile deformation,and it causes the increasing of the plastic deformation energy and delay of the fracture,which is considered as the reason for the increasing the ductility.展开更多
Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))products.Optimizing the C-C coupling process,the rate-determining step for C_(2)product generatio...Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))products.Optimizing the C-C coupling process,the rate-determining step for C_(2)product generation,is an important strategy to improve the production and selectivity of the C_(2)products.In this study,we determined that the local electric field can promote the C-C coupling reaction and enhance CO_(2)electroreduction to C_(2)products.First,finite-element simulations indicated that the high curvature of the Cu nanoneedles results in a large local electric field on their tips.Density functional theory(DFT)calculations proved that a large electric field can promote C-C coupling.Motivated by this prediction,we prepared a series of Cu catalysts with different curvatures.The Cu nanoneedles(NNs)exhibited the largest number of curvatures,followed by the Cu nanorods(NRs),and Cu nanoparticles(NPs).The Cu NNs contained the highest concentration of adsorbed K+,which resulted in the highest local electric field on the needles.CO adsorption sensor tests indicated that the Cu NNs exhibited the strongest CO adsorption ability,and in-situ Fourier-transform infrared spectroscopy(FTIR)showed the strongest*COCO and*CO signals for the Cu NNs.These experimental results demonstrate that high-curvature nanoneedles can induce a large local electric field,thus promoting C-C coupling.As a result,the Cu NNs show a maximum FEC_(2)of 44%for CO_(2)RR at a low potential(-0.6 V vs.RHE),which is approximately 2.2 times that of the Cu NPs.This work provides an effective strategy for enhancing the production of multi-carbon products during CO_(2)RR.展开更多
Our world is composed of various materials with different structures,where spin structures have been playing a pivotal role in spintronic devices of the contemporary information technology.Apart from conventional coll...Our world is composed of various materials with different structures,where spin structures have been playing a pivotal role in spintronic devices of the contemporary information technology.Apart from conventional collinear spin materials such as collinear ferromagnets and collinear antiferromagnetic ally coupled materials,noncollinear spintronic materials have emerged as hot spots of research attention due to exotic physical phenomena.In this review,we first introduce two types of noncollinear spin structures,i.e.,the chiral spin structure that yields real-space Berry phases and the coplanar noncollinear spin structure that could generate momentum-space Berry phases,and then move to relevant novel physical phenomena including topological Hall effect,anomalous Hall effect,multiferroic,Weyl fermions,spin-polarized current and spin Hall effect without spin-orbit coupling in these noncollinear spin systems.Afterward,we summarize and elaborate the electric-field control of the noncollinear spin structure and related physical effects,which could enable ultralow power spintronic devices in future.In the final outlook part,we emphasize the importance and possible routes for experimentally detecting the intriguing theoretically predicted spin-polarized current,verifying the spin Hall effect in the absence of spin-orbit coupling and exploring the anisotropic magnetoresistance and domain-wall-related magnetoresistance effects for noncollinear antiferromagnetic materials.展开更多
The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick supercon...The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick superconducting Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure with an onset transition temperature of~9.5 K. Photoluminescence measurements reveal that there is negligible oxygen vacancy creation in the SrTiO_(3) substrate during thin-film deposition and post chemical reduction for the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) heterostructure. It was found that the critical current density of the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure is relatively small, ~4×10^(3) A·cm^(-2). Although the surface steps of SrTiO_(3) substrates lead to an anisotropy for in-plane resistivity, the superconducting transition temperatures are almost the same. The out-of-plane magnetotransport measurements yield an upper critical field of~11.4 T and an estimated in-plane Ginzburg–Landau coherence length of~5.4 nm. High-field magnetotransport measurements up to 50 T reveal anisotropic critical fields at 1.8 K for three different measurement geometries and a complicated Hall effect. An electric field applied via the SrTiO_(3) substrate slightly varies the superconducting transition temperature. These experimental results could be useful for this rapidly developing field.展开更多
The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic and external electric-field induced spin-orbit coupling we...The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic and external electric-field induced spin-orbit coupling were investigated theoretically. Based on a unified semiclassical theoretical approach, it is shown that the total anomalous Hall conductivity can be expressed as the sum of three distinct contributions in the presence of these competing spin-orbit interactions, namely an intrinsic contribution determined by the Berry curvature in the momentum space, an extrinsic contribution determined by the modified Bloch band group velocity and an extrinsic contribution determined by spin-orbit-dependent impurity scattering. The characteristics of these competing contributions are discussed in detail in the paper.展开更多
Electric-field control of perpendicular magnetic anisotropy(PMA) is a feasible way to manipulate perpendicular magnetization,which is of great importance for realizing energy-efficient spintronics.Here,we propose a no...Electric-field control of perpendicular magnetic anisotropy(PMA) is a feasible way to manipulate perpendicular magnetization,which is of great importance for realizing energy-efficient spintronics.Here,we propose a novel approach to accomplish this task at room temperature by resistive switching(RS) via electrochemical metallization(ECM) in a device with the stack of Si/SiO_(2)/Ta/Pt/Ag/Mn-doped ZnO(MZO)/Pt/Co/Pt/ITO.By applying certain voltages,the device could be set at high-resistance-state(HRS) and low-resistance-state(LRS),accompanied with a larger and a smaller coercivity(H_(C)),respectively,which demonstrates a nonvolatile E-field control of PMA.Based on our previous studies and the present control experiments,the electric modulation of PMA can be briefly explained as follows.At LRS,the Ag conductive filaments form and pass through the entire MZO layer and finally reach the Pt/Co/Pt sandwich,leading to weakening of PMA and reduction of H_(C).In contrast,at HRS,most of the Ag filaments dissolve and leave away from the Pt/Co/Pt sandwich,causing partial recovery of PMA and an increase of H_(C).This work provides a new clue to designing low-power spintronic devices based on PMA films.展开更多
Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and non- volatile in-plane rotation of magnetic easy axis of -35° between the positive and negative electrical ...Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and non- volatile in-plane rotation of magnetic easy axis of -35° between the positive and negative electrical poling states is demonstrated in C040Fe40B20//（001）-cut Pb（Mgl/3Nb2/3）O3-25PbTiO3 （PMN-PT）. The specific magneto- electric coupling mechanism therein is experimentally verified to be related to the synchronous in-plane strain rotation induced by 109° ferroelastic domain switching in the （001）-cut PMN-PT substrate.展开更多
The electric-field tunability of dielectric constant （ε-E） in Sr1-xMnxTiO3 films （x = 0, 0.005, 0.010, 0.020 and 0.030） prepared by the metal organic decomposition method on Pt/Ti/SiO2/Si substrates is studied in...The electric-field tunability of dielectric constant （ε-E） in Sr1-xMnxTiO3 films （x = 0, 0.005, 0.010, 0.020 and 0.030） prepared by the metal organic decomposition method on Pt/Ti/SiO2/Si substrates is studied in the frequency range from 100Hz to 1MHz with different Mn contents at different temperatures. The frequencyindependent tunability increases strongly with decreasing the temperature from 300 K to 150K. The tunability （-31%） in thin films （x = 0.005） at 150K is obtained and the temperature for the same tunability in ceramics is about 60 K lower than the present one. This tunability is comparable with that in one of ferroelectric Sr1-1.sxBixTiO3 thin films. Similarly, the well-defined P（E） hysteresis 10013 and 2Pr （1.2 μC/cm^2） can be obtained at 300 K in Sr1-xMnxTiO3 films with z = 0.005. Both the existence of electric dipole or poled micro domain introduced by the doped Mn2＋ located in the off-center position at Sr sites and the strain between the thin film and the substrate are the origins of the tunable and polar behavior in Sr1-xMnxTiO3 films.展开更多
Effects of an electric field on CO oxidation of Au-embedded graphene are investigated using first-principles method. Results of our calculations show that the initial step of the reaction is more likely to proceed via...Effects of an electric field on CO oxidation of Au-embedded graphene are investigated using first-principles method. Results of our calculations show that the initial step of the reaction is more likely to proceed via the Langmuir-Hinshelwood mechanism in the presence of the field, and the reaction barrier can be tuned continuously by the electric field. However, the applied electric field makes it more difficult for the product of the reaction, CO2, to desorb from the reaction site. These two competing effects make an electric field not entirely advantageous in controlling the activity of Au-embedded graphene for CO oxidation reaction. Nevertheless, the findings of our study provide a basis for further investigation on control of chemical reactions by electric fields.展开更多
Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic(AFM)-ferromagnetic(FM)phase transition and(001)-oriented PMN-PT substrates has been investigated.Utilizing a uni...Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic(AFM)-ferromagnetic(FM)phase transition and(001)-oriented PMN-PT substrates has been investigated.Utilizing a unipolar electric field,the nonvolatile change in magnetization was nearly doubled compared with that obtained utilizing a conventional bipolar bias.Four stable nonvolatile magnetic states were obtained over a broad temperature span,from 320 to 390K,by adjusting the amplitude of the unipolar electric pulses,demonstrating the possibility of realizing a multistate nonvolatile magnetic memory in the FeRh/PMN-PT heterostructures.This work provides a new strategy for enhancing the magnetic response by utilizing unipolar electric fields and promotes the utilization of AFM-FM phase transition materials in multifunctional information storage and novel spintronic devices.展开更多
Subject Code:A04With the financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics,Tsinghua University recently publishe...Subject Code:A04With the financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics,Tsinghua University recently published their seminal work in Nature(2017,546:124—128).The work,titled“Electric-field control展开更多
With financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics in Tsinghua University published their seminal work recen...With financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics in Tsinghua University published their seminal work recently in the prestigious journal Nature(2017,546:124-128).The work。展开更多
Based on the Faraday’s Law, the shape evolution model was calculated depending on a function of time, and the influence of the variable current efficiency which was brought by the passivating electrolyte was included...Based on the Faraday’s Law, the shape evolution model was calculated depending on a function of time, and the influence of the variable current efficiency which was brought by the passivating electrolyte was included. The final shape determination was obtained by solving the model of electric-field distribution by the finite element method, at the same time flow parameters influencing on the shaping process were also considered. The results show that the experimental results are in close agreement with the theoretical ones.展开更多
Measurements of energetic particles obtained by the two geosynchronous satellites （1991-080 and LANL-97A） are performed to investigate the plasma injection boundary and source region during the magnetospheric substo...Measurements of energetic particles obtained by the two geosynchronous satellites （1991-080 and LANL-97A） are performed to investigate the plasma injection boundary and source region during the magnetospheric substorms. The measurement method is developed to allow remote sensing of the plasma injection time and the radial distance of injection boundaries by using measured energy dispersion and modelling particle drifts within the Volland-Stern electric field and the dipole magnetic field model. The radial distance of the injection boundary deduced from a dispersion event observed by the LANL-97A satellite on 14 June 1998 is 7.1RE, and the injection time agrees well with the substorm onset time identified by the Polar Ultraviolet Imager. The method has been applied to an event happened at 22.9 UT on 11 March 1998, when both the satellites （1991-080 and LANL-97A） observed the dispersionless character. The results indicate that the radial distance of injection source locates at 8.1RE at magnetotail, and particles move earthward from magnetotail into inner magnetosphere at 22.5 UT.展开更多
Taking the advantages of semiconducting properties and carrier-mediated ferromagnetism in(Ga,Mn)As,a giant modulation of magnetism via electric field in(Ga,Mn)As ultrathin film has been demonstrated.Specifically,huge ...Taking the advantages of semiconducting properties and carrier-mediated ferromagnetism in(Ga,Mn)As,a giant modulation of magnetism via electric field in(Ga,Mn)As ultrathin film has been demonstrated.Specifically,huge interfacial electric field is obtained by using ionic liquid as the gate dielectric.Both magnetization and transport measurements are employed to characterize the samples,while the transport data are used to analyze the electric filed effect on magnetism.Complete demagnetization of(Ga,Mn)As film is then realized by thinning its thickness down to ~2 nm,during which the degradation of ferromagnetism of(Ga,Mn)As ultrathin film induced by quantum confinement effect is suppressed by inserting a heavily-doped p-type GaAs buffer layer.The variation of the Curie temperature is more than 100 K,which is nearly 5-times larger than previous results.Our results provide a new pathway on the efficient electrical control of magnetism.展开更多
Non-thermal plasma at atmosphere was generated through glidarc discharge driven by magnetic field and observed by using a high speed charge coupled device （CCD） and photo multiplier tube （PMT）. The arc diameter pr...Non-thermal plasma at atmosphere was generated through glidarc discharge driven by magnetic field and observed by using a high speed charge coupled device （CCD） and photo multiplier tube （PMT）. The arc diameter projecting in the direction of arc motion （front-viewed diameter） and the diameter projecting in the perpendicular direction of arc motion （side-viewed diameter） were measured. The effect of both the arc current and the magnetic field was analysed. The front-viewed diameter was compared with the side-viewed one. Simultaneously the electricfield intensity was measured directly and analysed by considering the effect of the external magnetic field and arc current.展开更多
The optical absorption of GaAs nanorings （NRs） under adc electric field and a terahertz （THz） ac electric field applied in the plane containing the NRs is investigated theoretically. The NRs may enclose some magne...The optical absorption of GaAs nanorings （NRs） under adc electric field and a terahertz （THz） ac electric field applied in the plane containing the NRs is investigated theoretically. The NRs may enclose some magnetic flux in the presence of a magnetic field perpendicular to the NRs plane. Numerical calculation shows that the excitonic effects are essential to correctly describe the optical absorption in NRs. The applied lateral THz electric field, as well as the dc field leads to reduction, broadening and splitting of the exciton peak. In contrast to the presence of a dc field, significant optical absorption peak arises below the zero-field bandgap in the presence ofa THz electric field at a certain frequency. The optical absorption spectrum depends evidently on the frequency and amplitude of the applied THz field and on the magnetic flux threading the NRs. This promises potential applications of NRs for magneto-optical and THz electro-optical sensing.展开更多
We observe the photorefractivity without bias voltage or prepoling in a bifunctional photorefractive polymer. The maximum two-beam coupling gain is measured to be 126cm^-1 at zero bias voltage. The sample is considere...We observe the photorefractivity without bias voltage or prepoling in a bifunctional photorefractive polymer. The maximum two-beam coupling gain is measured to be 126cm^-1 at zero bias voltage. The sample is considered to be poled by the photoinduced longitudinal electric field, which is formed due to the light intensity gradient along the light path. The expression of the electric field was deduced. The energy transfer direction between two writing beams and light intensity dependence of the two-beam coupling gain coefficient is predicted to be consistent with the experimental results. Furthermore, the dependence of the two-beam coupling gain coefficient on external applied electrical field is measured and this experiment verifies the existence of the photoinduced longitudinal electric field.展开更多
It has been shown that a volume discharge is forming in non-uniform electric-field rough cathode and even anode without pre-ionization in SF6 and C2H6 mixtures. The discharge is presented with many diffuse channels at...It has been shown that a volume discharge is forming in non-uniform electric-field rough cathode and even anode without pre-ionization in SF6 and C2H6 mixtures. The discharge is presented with many diffuse channels attached to bright circular cathode spots that diverge towards the anode, with the channels overlapping, form a spatially uniform glow discharge. Self-Initiated Volume Discharge(SIVD) has been performed at a total mixture pressure up to 8 kPa and energy deposition up to 200 J/L. The experimental results indicate that Self-Sustained Volume Discharge(SSVD) in SF6 and C2H6 mixtures develops in the form of SIVD, which is promising for creation of high energy and pulse-periodic HF laser.展开更多
基金supported by the National Natural Science Foundation of China(22378285,92475117 and U21A20303)。
文摘Electrochemically switched ion exchange(ESIX)is an effective technology for extracting high-valueadded ions from dilute solutions.This study focuses on Li^(+)extraction by employing a comprehensive model to analyze interaction between fluidic dynamics,electric field and ion transport.The model combines Butler-Volmer equation modified by electroactive site concentration,Nernst-Planck equation and Navier-Stokes equation.It is found that the chamber width affects solution phase resistance,thereby altering the pote ntial distribution and influencing the current distribution within the membrane.A narrow chamber increases current density in the solid phase of the membrane,enhancing Li^(+) extraction.The solution flow-field not only enhances convective transport but also increases the current density in the solid phase,promoting Li^(+) extraction.There is a synergistic effect between fluid-flow-field and electric-field for ion separation,which is only significant when the chamber width is greater than 2 mm.The synergistic mechanism differs from that in the capacitive deionization system.Therefore,the performance decline caused by a wide chamber can be compensated for by increasing the fluid-flow rate,utilizing the synergistic effect between the flu id-flow-field and electric-field to optimize the lithium extraction efficiency in the ESIX system.
文摘The effects of electric-field treatment on the microstructure and deformation behavior of a nickel-base superalloy were summarized.The results show that the electric-field treatment increases the ductility of the superalloy but has no evident influence on its static strength at both room and elevated temperatures,while,the strength increases but elongation changes weekly with the increasing tensile strain rate.It is found that the direction of microcrack propagation can be changed by the presence of the annealing twins during the tensile deformation,and it causes the increasing of the plastic deformation energy and delay of the fracture,which is considered as the reason for the increasing the ductility.
文摘Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))products.Optimizing the C-C coupling process,the rate-determining step for C_(2)product generation,is an important strategy to improve the production and selectivity of the C_(2)products.In this study,we determined that the local electric field can promote the C-C coupling reaction and enhance CO_(2)electroreduction to C_(2)products.First,finite-element simulations indicated that the high curvature of the Cu nanoneedles results in a large local electric field on their tips.Density functional theory(DFT)calculations proved that a large electric field can promote C-C coupling.Motivated by this prediction,we prepared a series of Cu catalysts with different curvatures.The Cu nanoneedles(NNs)exhibited the largest number of curvatures,followed by the Cu nanorods(NRs),and Cu nanoparticles(NPs).The Cu NNs contained the highest concentration of adsorbed K+,which resulted in the highest local electric field on the needles.CO adsorption sensor tests indicated that the Cu NNs exhibited the strongest CO adsorption ability,and in-situ Fourier-transform infrared spectroscopy(FTIR)showed the strongest*COCO and*CO signals for the Cu NNs.These experimental results demonstrate that high-curvature nanoneedles can induce a large local electric field,thus promoting C-C coupling.As a result,the Cu NNs show a maximum FEC_(2)of 44%for CO_(2)RR at a low potential(-0.6 V vs.RHE),which is approximately 2.2 times that of the Cu NPs.This work provides an effective strategy for enhancing the production of multi-carbon products during CO_(2)RR.
基金financially supported by the National Natural Science Foundation of China(Nos.51822101,51861135104,51771009 and 11704018).
文摘Our world is composed of various materials with different structures,where spin structures have been playing a pivotal role in spintronic devices of the contemporary information technology.Apart from conventional collinear spin materials such as collinear ferromagnets and collinear antiferromagnetic ally coupled materials,noncollinear spintronic materials have emerged as hot spots of research attention due to exotic physical phenomena.In this review,we first introduce two types of noncollinear spin structures,i.e.,the chiral spin structure that yields real-space Berry phases and the coplanar noncollinear spin structure that could generate momentum-space Berry phases,and then move to relevant novel physical phenomena including topological Hall effect,anomalous Hall effect,multiferroic,Weyl fermions,spin-polarized current and spin Hall effect without spin-orbit coupling in these noncollinear spin systems.Afterward,we summarize and elaborate the electric-field control of the noncollinear spin structure and related physical effects,which could enable ultralow power spintronic devices in future.In the final outlook part,we emphasize the importance and possible routes for experimentally detecting the intriguing theoretically predicted spin-polarized current,verifying the spin Hall effect in the absence of spin-orbit coupling and exploring the anisotropic magnetoresistance and domain-wall-related magnetoresistance effects for noncollinear antiferromagnetic materials.
基金financially supported by the National Natural Science Foundation of China(Nos.51822101,51861135104 and 51771009)。
文摘The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick superconducting Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure with an onset transition temperature of~9.5 K. Photoluminescence measurements reveal that there is negligible oxygen vacancy creation in the SrTiO_(3) substrate during thin-film deposition and post chemical reduction for the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) heterostructure. It was found that the critical current density of the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure is relatively small, ~4×10^(3) A·cm^(-2). Although the surface steps of SrTiO_(3) substrates lead to an anisotropy for in-plane resistivity, the superconducting transition temperatures are almost the same. The out-of-plane magnetotransport measurements yield an upper critical field of~11.4 T and an estimated in-plane Ginzburg–Landau coherence length of~5.4 nm. High-field magnetotransport measurements up to 50 T reveal anisotropic critical fields at 1.8 K for three different measurement geometries and a complicated Hall effect. An electric field applied via the SrTiO_(3) substrate slightly varies the superconducting transition temperature. These experimental results could be useful for this rapidly developing field.
基金supported by the National Natural Science Foundation of China (Grant No.10874049)
文摘The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic and external electric-field induced spin-orbit coupling were investigated theoretically. Based on a unified semiclassical theoretical approach, it is shown that the total anomalous Hall conductivity can be expressed as the sum of three distinct contributions in the presence of these competing spin-orbit interactions, namely an intrinsic contribution determined by the Berry curvature in the momentum space, an extrinsic contribution determined by the modified Bloch band group velocity and an extrinsic contribution determined by spin-orbit-dependent impurity scattering. The characteristics of these competing contributions are discussed in detail in the paper.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2022YFA1403602)the National Natural Science Foundation of China (Grant Nos. 51971109, 52025012, and 52001169)。
文摘Electric-field control of perpendicular magnetic anisotropy(PMA) is a feasible way to manipulate perpendicular magnetization,which is of great importance for realizing energy-efficient spintronics.Here,we propose a novel approach to accomplish this task at room temperature by resistive switching(RS) via electrochemical metallization(ECM) in a device with the stack of Si/SiO_(2)/Ta/Pt/Ag/Mn-doped ZnO(MZO)/Pt/Co/Pt/ITO.By applying certain voltages,the device could be set at high-resistance-state(HRS) and low-resistance-state(LRS),accompanied with a larger and a smaller coercivity(H_(C)),respectively,which demonstrates a nonvolatile E-field control of PMA.Based on our previous studies and the present control experiments,the electric modulation of PMA can be briefly explained as follows.At LRS,the Ag conductive filaments form and pass through the entire MZO layer and finally reach the Pt/Co/Pt sandwich,leading to weakening of PMA and reduction of H_(C).In contrast,at HRS,most of the Ag filaments dissolve and leave away from the Pt/Co/Pt sandwich,causing partial recovery of PMA and an increase of H_(C).This work provides a new clue to designing low-power spintronic devices based on PMA films.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11374010 and 11434009the Fundamental Research Funds for the Central Universities
文摘Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and non- volatile in-plane rotation of magnetic easy axis of -35° between the positive and negative electrical poling states is demonstrated in C040Fe40B20//（001）-cut Pb（Mgl/3Nb2/3）O3-25PbTiO3 （PMN-PT）. The specific magneto- electric coupling mechanism therein is experimentally verified to be related to the synchronous in-plane strain rotation induced by 109° ferroelastic domain switching in the （001）-cut PMN-PT substrate.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51225201,61271078,and 51102133the National Basic Research Program of China under Grant No 2015CB921201+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central Universities
文摘The electric-field tunability of dielectric constant （ε-E） in Sr1-xMnxTiO3 films （x = 0, 0.005, 0.010, 0.020 and 0.030） prepared by the metal organic decomposition method on Pt/Ti/SiO2/Si substrates is studied in the frequency range from 100Hz to 1MHz with different Mn contents at different temperatures. The frequencyindependent tunability increases strongly with decreasing the temperature from 300 K to 150K. The tunability （-31%） in thin films （x = 0.005） at 150K is obtained and the temperature for the same tunability in ceramics is about 60 K lower than the present one. This tunability is comparable with that in one of ferroelectric Sr1-1.sxBixTiO3 thin films. Similarly, the well-defined P（E） hysteresis 10013 and 2Pr （1.2 μC/cm^2） can be obtained at 300 K in Sr1-xMnxTiO3 films with z = 0.005. Both the existence of electric dipole or poled micro domain introduced by the doped Mn2＋ located in the off-center position at Sr sites and the strain between the thin film and the substrate are the origins of the tunable and polar behavior in Sr1-xMnxTiO3 films.
基金supported by the National Research Foundation (Singapore) Competitive Research Program (Grant No. NRF-G-CRP 2007-05)
文摘Effects of an electric field on CO oxidation of Au-embedded graphene are investigated using first-principles method. Results of our calculations show that the initial step of the reaction is more likely to proceed via the Langmuir-Hinshelwood mechanism in the presence of the field, and the reaction barrier can be tuned continuously by the electric field. However, the applied electric field makes it more difficult for the product of the reaction, CO2, to desorb from the reaction site. These two competing effects make an electric field not entirely advantageous in controlling the activity of Au-embedded graphene for CO oxidation reaction. Nevertheless, the findings of our study provide a basis for further investigation on control of chemical reactions by electric fields.
基金supported by the National Key Research and Development Program of China(Grant Nos.2020YFA0711502,2019YFA0704900,2018YFA0305704,and 2017YFB0702704)National Natural Science Foundation of China(Grant Nos.52088101,U1832219,51771223,51971240,and 51671022)+3 种基金China Postdoctoral Science Foundation(Grant No.2021M690346)Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange&Growth Program(Grant Nos.FRF-GF-20-08B,and QNXM20210014)State Key Lab of Advanced Metals and Materials(Grant No.2019-Z11)Key Program and Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB33030200)。
文摘Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic(AFM)-ferromagnetic(FM)phase transition and(001)-oriented PMN-PT substrates has been investigated.Utilizing a unipolar electric field,the nonvolatile change in magnetization was nearly doubled compared with that obtained utilizing a conventional bipolar bias.Four stable nonvolatile magnetic states were obtained over a broad temperature span,from 320 to 390K,by adjusting the amplitude of the unipolar electric pulses,demonstrating the possibility of realizing a multistate nonvolatile magnetic memory in the FeRh/PMN-PT heterostructures.This work provides a new strategy for enhancing the magnetic response by utilizing unipolar electric fields and promotes the utilization of AFM-FM phase transition materials in multifunctional information storage and novel spintronic devices.
文摘Subject Code:A04With the financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics,Tsinghua University recently published their seminal work in Nature(2017,546:124—128).The work,titled“Electric-field control
文摘With financial support from the National Natural Science Foundation of China,a research team led by Associate Professor Yu Pu(于浦)at the Department of Physics in Tsinghua University published their seminal work recently in the prestigious journal Nature(2017,546:124-128).The work。
文摘Based on the Faraday’s Law, the shape evolution model was calculated depending on a function of time, and the influence of the variable current efficiency which was brought by the passivating electrolyte was included. The final shape determination was obtained by solving the model of electric-field distribution by the finite element method, at the same time flow parameters influencing on the shaping process were also considered. The results show that the experimental results are in close agreement with the theoretical ones.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40390150, 40674094 and 40523006, and the National Basic Research Programme of China under Grant No 2006CB806305.
文摘Measurements of energetic particles obtained by the two geosynchronous satellites （1991-080 and LANL-97A） are performed to investigate the plasma injection boundary and source region during the magnetospheric substorms. The measurement method is developed to allow remote sensing of the plasma injection time and the radial distance of injection boundaries by using measured energy dispersion and modelling particle drifts within the Volland-Stern electric field and the dipole magnetic field model. The radial distance of the injection boundary deduced from a dispersion event observed by the LANL-97A satellite on 14 June 1998 is 7.1RE, and the injection time agrees well with the substorm onset time identified by the Polar Ultraviolet Imager. The method has been applied to an event happened at 22.9 UT on 11 March 1998, when both the satellites （1991-080 and LANL-97A） observed the dispersionless character. The results indicate that the radial distance of injection source locates at 8.1RE at magnetotail, and particles move earthward from magnetotail into inner magnetosphere at 22.5 UT.
基金supported by MOST (Grant No. 2017YFB0405701)NSFC (Grants Nos. U1632264 and 11704374)the Key Research Project of Frontier Science of Chinese Academy of Science (Grant No. QYZDY-SSW-JSC015)
文摘Taking the advantages of semiconducting properties and carrier-mediated ferromagnetism in(Ga,Mn)As,a giant modulation of magnetism via electric field in(Ga,Mn)As ultrathin film has been demonstrated.Specifically,huge interfacial electric field is obtained by using ionic liquid as the gate dielectric.Both magnetization and transport measurements are employed to characterize the samples,while the transport data are used to analyze the electric filed effect on magnetism.Complete demagnetization of(Ga,Mn)As film is then realized by thinning its thickness down to ~2 nm,during which the degradation of ferromagnetism of(Ga,Mn)As ultrathin film induced by quantum confinement effect is suppressed by inserting a heavily-doped p-type GaAs buffer layer.The variation of the Curie temperature is more than 100 K,which is nearly 5-times larger than previous results.Our results provide a new pathway on the efficient electrical control of magnetism.
基金National Natural Science Foundation of China(No.10375065)Natural Science Foundation of Anhui Province(No.03045102)
文摘Non-thermal plasma at atmosphere was generated through glidarc discharge driven by magnetic field and observed by using a high speed charge coupled device （CCD） and photo multiplier tube （PMT）. The arc diameter projecting in the direction of arc motion （front-viewed diameter） and the diameter projecting in the perpendicular direction of arc motion （side-viewed diameter） were measured. The effect of both the arc current and the magnetic field was analysed. The front-viewed diameter was compared with the side-viewed one. Simultaneously the electricfield intensity was measured directly and analysed by considering the effect of the external magnetic field and arc current.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10390161 and 30370420.
文摘The optical absorption of GaAs nanorings （NRs） under adc electric field and a terahertz （THz） ac electric field applied in the plane containing the NRs is investigated theoretically. The NRs may enclose some magnetic flux in the presence of a magnetic field perpendicular to the NRs plane. Numerical calculation shows that the excitonic effects are essential to correctly describe the optical absorption in NRs. The applied lateral THz electric field, as well as the dc field leads to reduction, broadening and splitting of the exciton peak. In contrast to the presence of a dc field, significant optical absorption peak arises below the zero-field bandgap in the presence ofa THz electric field at a certain frequency. The optical absorption spectrum depends evidently on the frequency and amplitude of the applied THz field and on the magnetic flux threading the NRs. This promises potential applications of NRs for magneto-optical and THz electro-optical sensing.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60407004, 10521002, 10434020, 60378012, 90206003, 10328407 and 90101027, the National Key Basic Research Special Foundation （NKBRSF） of China under Grant No TG1999075207.
文摘We observe the photorefractivity without bias voltage or prepoling in a bifunctional photorefractive polymer. The maximum two-beam coupling gain is measured to be 126cm^-1 at zero bias voltage. The sample is considered to be poled by the photoinduced longitudinal electric field, which is formed due to the light intensity gradient along the light path. The expression of the electric field was deduced. The energy transfer direction between two writing beams and light intensity dependence of the two-beam coupling gain coefficient is predicted to be consistent with the experimental results. Furthermore, the dependence of the two-beam coupling gain coefficient on external applied electrical field is measured and this experiment verifies the existence of the photoinduced longitudinal electric field.
基金Supported by the National Natural Science Fundation of China(Nos.60708005,1178029)
文摘It has been shown that a volume discharge is forming in non-uniform electric-field rough cathode and even anode without pre-ionization in SF6 and C2H6 mixtures. The discharge is presented with many diffuse channels attached to bright circular cathode spots that diverge towards the anode, with the channels overlapping, form a spatially uniform glow discharge. Self-Initiated Volume Discharge(SIVD) has been performed at a total mixture pressure up to 8 kPa and energy deposition up to 200 J/L. The experimental results indicate that Self-Sustained Volume Discharge(SSVD) in SF6 and C2H6 mixtures develops in the form of SIVD, which is promising for creation of high energy and pulse-periodic HF laser.
