Doped HfO_(2)as an emerging ferroelectric material,holds considerable promise for non-volatile memory applications.Epitaxial growth of doped HfO_(2)thin films is widely adopted as an effective technique for revealing ...Doped HfO_(2)as an emerging ferroelectric material,holds considerable promise for non-volatile memory applications.Epitaxial growth of doped HfO_(2)thin films is widely adopted as an effective technique for revealing the intrinsic ferroelectric properties.In this study,based on systematic structural,chemical and electrical investigations,the influences of Mn doping and substrate orientation on ferroelectric properties of Mn-doped HfO_(2)epitaxial thin films are investigated.The results demonstrate that Mn-doped HfO_(2)thin films with orthorhombic phase can be epitaxially grown along[111]out-of-plane direction on both SrTiO_(3)(001)and(110)substrates,and 10%Mn-doping significantly stabilizes the orthorhombic polar phase and enhances the ferroelectric polarization.Interestingly,compared to the films on SrTiO_(3)(001)substrate,the better crystallinity and reduction of oxygen vacancy amount in Mn-doped HfO_(2)films grown on the SrTiO_(3)(110)substrate are observed,which enhance the remanent polarization and reduce the coercive field.It provides an effective approach for the controllable regulation of defects and the enhancement of intrinsic ferroelectricity in HfO_(2)-based materials.展开更多
Ruddlesden-Popper iridate Sr_(3)Ir_(2)O_(7)is a spin-orbit coupled Mott insulator.Hole doped Sr_(3)Ir_(2)O_(7)provides an ideal platform to study the exotic quantum phenomena that occur near the metal-insulator transi...Ruddlesden-Popper iridate Sr_(3)Ir_(2)O_(7)is a spin-orbit coupled Mott insulator.Hole doped Sr_(3)Ir_(2)O_(7)provides an ideal platform to study the exotic quantum phenomena that occur near the metal-insulator transition(MIT)region.Rh substitution of Ir is an effective method to induce hole doping into Sr_(3)Ir_(2)O_(7).However,the highest doping level reported in Sr_(3)(Ir_(1-x)Rh_(x))_(2)O_(7)single crystals was only around 3%,which is far from the MIT region.In this paper,we report the successful growth of single crystals of Sr3(Ir_(1-x)Rh_(x))_(2)O_(7)with a doping level of~9%.The samples have been fully characterized,demonstrating the high quality of the single crystals.Transport measurements have been carried out,confirming the tendency of MIT in these samples.The electronic structure has also been examined by angle-resolved photoemission spectroscopy(ARPES)measurements.Our results establish a platform to investigate the heavily hole doped Sr_(3)Ir_(2)O_(7) compound,which also provide new insights into the MIT with hole doping in this material system.展开更多
The superior dielectric and ferroelectric properties of HfO_(2)-based thin films,coupled with excellent silicon compatibility,position them as highly attractive candidates for dynamic and ferroelectric random-access m...The superior dielectric and ferroelectric properties of HfO_(2)-based thin films,coupled with excellent silicon compatibility,position them as highly attractive candidates for dynamic and ferroelectric random-access memories(DRAM and FeRAM).However,simultaneously achieving high dielectric constant(κ)and strong ferroelectricity in HfO_(2)-based films presents a challenge,as high-κand ferroelectricity are associated with the tetragonal and orthorhombic phases,respectively.In this study,we report both the good ferroelectric and dielectric properties obtained in W/Hf_(0.5)Zr_(0.5)O_(2)(HZO∼6.5 nm)/W with morphotropic phase boundary structure by optimizing stacking sequence of HfO_(2)and ZrO_(2)sublayers.Notably,by alternating stacking of 1-cycle HfO_(2)with 1-cycle ZrO_(2)sublayers((1-HfO_(2))/(1-ZrO_(2))),high-κ(>50)and large polarization(2Pr>40μC/cm2,after wake-up)can be achieved.Besides,the(1-HfO_(2))/(1-ZrO_(2))stacking configuration presents better thermal stability compared to other stacking sequences.Furthermore,the incorporation of an Al_(2)O_(3)layer leads to a low leakage current density(<10^(−7)A/cm^(2)at 0.65 V)and high dielectric endurance over 1013 cycles(operating voltage∼0.5 V).A low equivalent oxide thickness(EOT∼0.53 nm)and considerable polarization with low leakage are simultaneously achieved.These results highlight the potential of HfO_(2)-based films with optimized structural stacking as a trade-off approach for integrating DRAM and FeRAM on one-chip.展开更多
Flexible hafnia-based ferroelectric memories are arousing much interest with the ever-growing demands for nonvolatile data storage in wearable electronic devices.Here,high-quality flexible Hf_(0.5)Zr_(0.5)O_(2)membran...Flexible hafnia-based ferroelectric memories are arousing much interest with the ever-growing demands for nonvolatile data storage in wearable electronic devices.Here,high-quality flexible Hf_(0.5)Zr_(0.5)O_(2)membranes with robust ferroelectricity were fabricated on inorganic pliable mica substrates via an atomic layer deposition technique.The flexible Hf_(0.5)Zr_(0.5)O_(2) thin membranes with a thickness of∼8 nm exhibit a high remanent polarization of∼16μC/cm^(2),which possess very robust polarization switching endurance(>10^(10) cycles,two orders of magnitude better than reported flexible HfO_(2)-based films)and superior retention ability(expected>10 years).In particular,stable ferroelectric polarization as well as excellent endurance and retention performance show negligible degradations under 6 mm radius bending conditions or after 10^(4) bending cycles with a 6 mm bending radius.These results mark a crucial step in the development of flexible hafnium oxide-based ferroelectric memories for wearable electronic devices.展开更多
Ferroelectric tunnel junctions(FTJs)as the artificial synaptic devices have been considered promising for constructing brain-inspired neuromorphic computing systems.However,the memristive synapses based on the flexibl...Ferroelectric tunnel junctions(FTJs)as the artificial synaptic devices have been considered promising for constructing brain-inspired neuromorphic computing systems.However,the memristive synapses based on the flexible FTJs have been rarely studied.Here,we report a flexible FTJ memristor grown on a mica substrate,which consists of an ultrathin ferroelectric barrier of BiFeO_(3),a semiconducting layer of ZnO,and an electrode of SrRuO_(3).The obtained flexible FTJ memristor exhibits stable voltage-tuned multistates,and the resistive switchings are robust after 10^(3) bending cycles.The capability of the FTJ as a flexible synaptic device is demonstrated by the functionality of the spike-timing-dependent plasticity with bending,and the accurate conductance manipulation with small nonlinearity(-0.24)and low cycle-to-cycle variation(1.77%)is also realized.Especially,artificial neural network simulations based on experimental device behaviors reveal that the high recognition accuracies up to 92.8%and 86.2%are obtained for handwritten digits and images,respectively,which are close to the performances for ideal memristors.This work highlights the potential applications of FTJ as flexible electronics for data storage and processing.展开更多
Although the basic concept was proposed only about 10 years ago,multiferroic tunnel junctions(MFTJs)with a ferroelectric barrier sandwiched between two ferromagnetic electrodes have already drawn considerable interest...Although the basic concept was proposed only about 10 years ago,multiferroic tunnel junctions(MFTJs)with a ferroelectric barrier sandwiched between two ferromagnetic electrodes have already drawn considerable interests,driven mainly by its potential applications in multi-level memories and electric field controlled spintronics.The purpose of this article is to review the recent progress of all-perovskite MFTJs.Starting from the key functional properties of the tunneling magnetoresistance,tunneling electroresistance,and tunneling electromagnetoresistance effects,we discuss the main origins of the tunneling electroresistance effect,recent progress in achieving multilevel resistance states in a single device,and the electrical control of spin polarization and transport through the ferroelectric polarization reversal of the tunneling barrier.展开更多
Room temperature electric field controlled magnetism is extremely promising for the next-generation high-performance spintronic devices.Here,based on the ferroelectric switching driven oxygen ion migration in the Ta/C...Room temperature electric field controlled magnetism is extremely promising for the next-generation high-performance spintronic devices.Here,based on the ferroelectric switching driven oxygen ion migration in the Ta/Co/BiFeO_(3)/SrRuO_(3) heterostructures,the magnetic moment,magnetic coercive field,exchange bias field,and junction resistance are reversibly manipulated by tuning the ferroelectric polarization of the BiFeO_(3) layer.All these phenomena are consistently explained by the oxygen ion migration induced CoOx/Co redox effect,which is evidenced by the synchrotron X-ray absorption spectroscopy measurements.Interestingly,owing to the controllable ferroelectric switching dynamics of the BiFeO_(3) thin film,the magnetic coercive field of the Co thin film can be continuously and precisely tuned by controlling the ferroelectric polarization of the BiFeO_(3) thin film,and the manipulating speed of the voltage control of magnetism can be fast to 100 ns.This nonvolatile,stable,reversible,fast,and reproducible voltage control of magnetism shows great potential for designing low-power and high-speed spintronics.展开更多
Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnet...Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges.Herein,we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS2 bilayer with substitutional doping of Co ion,by introducing sulfur vacancy(V_(s))to modulate the interlayer electronic coupling.This strategy could transform the interlayer exchange interaction from antiferromagnetism(AFM)to ferromagnetism(FM),as revealed by the magnetic measurements.Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and Vs-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers,and also enhances the intralayer FM.Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional(2D)magnetic materials.展开更多
Optical control of exotic properties in strongly correlated electron materials is very attractive owing to their potential applications in optical and electronic devices.Herein,we demonstrate a vertical heterojunction...Optical control of exotic properties in strongly correlated electron materials is very attractive owing to their potential applications in optical and electronic devices.Herein,we demonstrate a vertical heterojunction made of a correlated electron oxide thin film VO_(2) and a conductive 0.05 wt% Nb-doped TiO_(2) single crystal,whose metal-insulator transition(MIT)across the nanoscale heterointerface can be efficiently modulated by visible light irradiation.The magnitude of the MIT decreases from ~350 in the dark state to ~7 in the illuminated state,obeying a power law with respect to the light power density.The junction resistance is switched in a reversible and synchronous manner by turning light on and off.The optical tunability of it is also exponentially proportional to the light power density,and a 320-fold on/off ratio is achieved with an irradiance of 65.6 mW cm^(-2) below the MIT temperature.While the VO_(2) thin film is metallic above the MIT temperature,the optical tunability is remarkably weakened,with a one-fold change remaining under light illumination.These results are co-attributed to a net reduction(~15 meV)in the apparent barrier height and the photocarrier-injection-induced metallization of the VO_(2) heterointerface through a photovoltaic effect,which is induced by deep defect level transition upon the visible light irradiance at low temperature.Additionally,the optical tunability is minimal,resulting from the quite weak modulation of the already metallic band structure in the Schottky-type junction above the MIT temperature.This work enables a remotely optical scheme to manipulate the MIT,implying potential uncooled photodetection and photoswitch applications.展开更多
Modern electronics and electric power grids require high performance polymer-based dielectric nanocomposites.To realize large-scale applications,the energy density of nanocomposites needs to be further increased.Here,...Modern electronics and electric power grids require high performance polymer-based dielectric nanocomposites.To realize large-scale applications,the energy density of nanocomposites needs to be further increased.Here,we demonstrate a remarkable improvement in energy density of poly(vinylidene fluoride)(PVDF)matrix upon the incorporation of high-k Bi_(4.2)K_(0.8)Fe_(2)O_(9+δ)(BKFO)nanobelts.High aspect ratio BKFO nanobelts can enhance the Young's moduli of the nanocomposites and increase the path tortuosity of electrical trees,which are favorable for increasing the breakdown strength of the system.Thus,the dielectric constant and breakdown strength increase simultaneously at a low volume fraction(0.35 vol%)of BKFO nanobelts,and an ultrahigh recoverable energy density of 25.4 J/cm^(3) is achieved.These results provide a strategy to develop high performance flexible high-energy-density devices.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52125204,52250281,52422209,92163210,and U21A2066)the Na-tional Key Research and Development Program of China(Grant Nos.2024YFA1208601,2022YFB3807602,and 2022YFB3807604).
文摘Doped HfO_(2)as an emerging ferroelectric material,holds considerable promise for non-volatile memory applications.Epitaxial growth of doped HfO_(2)thin films is widely adopted as an effective technique for revealing the intrinsic ferroelectric properties.In this study,based on systematic structural,chemical and electrical investigations,the influences of Mn doping and substrate orientation on ferroelectric properties of Mn-doped HfO_(2)epitaxial thin films are investigated.The results demonstrate that Mn-doped HfO_(2)thin films with orthorhombic phase can be epitaxially grown along[111]out-of-plane direction on both SrTiO_(3)(001)and(110)substrates,and 10%Mn-doping significantly stabilizes the orthorhombic polar phase and enhances the ferroelectric polarization.Interestingly,compared to the films on SrTiO_(3)(001)substrate,the better crystallinity and reduction of oxygen vacancy amount in Mn-doped HfO_(2)films grown on the SrTiO_(3)(110)substrate are observed,which enhance the remanent polarization and reduce the coercive field.It provides an effective approach for the controllable regulation of defects and the enhancement of intrinsic ferroelectricity in HfO_(2)-based materials.
基金supported by the USTC start-up fundthe National Natural Science Foundation of China(Grant Nos.12074358 and 12004363)+2 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.WK3510000008 and WK2030000035)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302802)supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Contract No.DEAC02-76SF00515。
文摘Ruddlesden-Popper iridate Sr_(3)Ir_(2)O_(7)is a spin-orbit coupled Mott insulator.Hole doped Sr_(3)Ir_(2)O_(7)provides an ideal platform to study the exotic quantum phenomena that occur near the metal-insulator transition(MIT)region.Rh substitution of Ir is an effective method to induce hole doping into Sr_(3)Ir_(2)O_(7).However,the highest doping level reported in Sr_(3)(Ir_(1-x)Rh_(x))_(2)O_(7)single crystals was only around 3%,which is far from the MIT region.In this paper,we report the successful growth of single crystals of Sr3(Ir_(1-x)Rh_(x))_(2)O_(7)with a doping level of~9%.The samples have been fully characterized,demonstrating the high quality of the single crystals.Transport measurements have been carried out,confirming the tendency of MIT in these samples.The electronic structure has also been examined by angle-resolved photoemission spectroscopy(ARPES)measurements.Our results establish a platform to investigate the heavily hole doped Sr_(3)Ir_(2)O_(7) compound,which also provide new insights into the MIT with hole doping in this material system.
基金supported by the National Natural Science Foundation of China(U21A2066,52250281,52422209,52125204 and 52372128)the National Key Research and Development Program of China(2022YFB3807602 and 2022YFB3807604)the Fundamental Research Funds for the Central Universities(No.WK2030000070).
文摘The superior dielectric and ferroelectric properties of HfO_(2)-based thin films,coupled with excellent silicon compatibility,position them as highly attractive candidates for dynamic and ferroelectric random-access memories(DRAM and FeRAM).However,simultaneously achieving high dielectric constant(κ)and strong ferroelectricity in HfO_(2)-based films presents a challenge,as high-κand ferroelectricity are associated with the tetragonal and orthorhombic phases,respectively.In this study,we report both the good ferroelectric and dielectric properties obtained in W/Hf_(0.5)Zr_(0.5)O_(2)(HZO∼6.5 nm)/W with morphotropic phase boundary structure by optimizing stacking sequence of HfO_(2)and ZrO_(2)sublayers.Notably,by alternating stacking of 1-cycle HfO_(2)with 1-cycle ZrO_(2)sublayers((1-HfO_(2))/(1-ZrO_(2))),high-κ(>50)and large polarization(2Pr>40μC/cm2,after wake-up)can be achieved.Besides,the(1-HfO_(2))/(1-ZrO_(2))stacking configuration presents better thermal stability compared to other stacking sequences.Furthermore,the incorporation of an Al_(2)O_(3)layer leads to a low leakage current density(<10^(−7)A/cm^(2)at 0.65 V)and high dielectric endurance over 1013 cycles(operating voltage∼0.5 V).A low equivalent oxide thickness(EOT∼0.53 nm)and considerable polarization with low leakage are simultaneously achieved.These results highlight the potential of HfO_(2)-based films with optimized structural stacking as a trade-off approach for integrating DRAM and FeRAM on one-chip.
基金supported by the National Key Research and Development Program of China(2022YFB3807604 and 2019YFA0307900)the National Natural Science Foundation of China(U21A2066,52250281,52125204 and 92163210)the Fundamental Research Funds for the Central Universities(WK2030000035),and this work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘Flexible hafnia-based ferroelectric memories are arousing much interest with the ever-growing demands for nonvolatile data storage in wearable electronic devices.Here,high-quality flexible Hf_(0.5)Zr_(0.5)O_(2)membranes with robust ferroelectricity were fabricated on inorganic pliable mica substrates via an atomic layer deposition technique.The flexible Hf_(0.5)Zr_(0.5)O_(2) thin membranes with a thickness of∼8 nm exhibit a high remanent polarization of∼16μC/cm^(2),which possess very robust polarization switching endurance(>10^(10) cycles,two orders of magnitude better than reported flexible HfO_(2)-based films)and superior retention ability(expected>10 years).In particular,stable ferroelectric polarization as well as excellent endurance and retention performance show negligible degradations under 6 mm radius bending conditions or after 10^(4) bending cycles with a 6 mm bending radius.These results mark a crucial step in the development of flexible hafnium oxide-based ferroelectric memories for wearable electronic devices.
基金supported by the National Key Research and Development Program of China(2016YFA0300103 and 2019YFA0307900)National Natural Science Foundation of China(51790491,51972296 and 21521001)+1 种基金the Fundamental Research Funds for the Central Universities(WK2030000035)State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China。
文摘Ferroelectric tunnel junctions(FTJs)as the artificial synaptic devices have been considered promising for constructing brain-inspired neuromorphic computing systems.However,the memristive synapses based on the flexible FTJs have been rarely studied.Here,we report a flexible FTJ memristor grown on a mica substrate,which consists of an ultrathin ferroelectric barrier of BiFeO_(3),a semiconducting layer of ZnO,and an electrode of SrRuO_(3).The obtained flexible FTJ memristor exhibits stable voltage-tuned multistates,and the resistive switchings are robust after 10^(3) bending cycles.The capability of the FTJ as a flexible synaptic device is demonstrated by the functionality of the spike-timing-dependent plasticity with bending,and the accurate conductance manipulation with small nonlinearity(-0.24)and low cycle-to-cycle variation(1.77%)is also realized.Especially,artificial neural network simulations based on experimental device behaviors reveal that the high recognition accuracies up to 92.8%and 86.2%are obtained for handwritten digits and images,respectively,which are close to the performances for ideal memristors.This work highlights the potential applications of FTJ as flexible electronics for data storage and processing.
基金The work at PSU was supported in part by the DOE(Grant No.DE-FG02-08ER4653)the NSF(Grant No.DMR-1411166)The work at USTC was supported by NSFC and NBRPC(2016YFA0300103).
文摘Although the basic concept was proposed only about 10 years ago,multiferroic tunnel junctions(MFTJs)with a ferroelectric barrier sandwiched between two ferromagnetic electrodes have already drawn considerable interests,driven mainly by its potential applications in multi-level memories and electric field controlled spintronics.The purpose of this article is to review the recent progress of all-perovskite MFTJs.Starting from the key functional properties of the tunneling magnetoresistance,tunneling electroresistance,and tunneling electromagnetoresistance effects,we discuss the main origins of the tunneling electroresistance effect,recent progress in achieving multilevel resistance states in a single device,and the electrical control of spin polarization and transport through the ferroelectric polarization reversal of the tunneling barrier.
基金supported by the National Key Research and Development Program of China(2019YFA0307900)National Natural Science Foundation of China(51790491,U21A2066,52125204,and 92163210)+1 种基金the fundamental research funds for the central universities(WK2030000035)this work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘Room temperature electric field controlled magnetism is extremely promising for the next-generation high-performance spintronic devices.Here,based on the ferroelectric switching driven oxygen ion migration in the Ta/Co/BiFeO_(3)/SrRuO_(3) heterostructures,the magnetic moment,magnetic coercive field,exchange bias field,and junction resistance are reversibly manipulated by tuning the ferroelectric polarization of the BiFeO_(3) layer.All these phenomena are consistently explained by the oxygen ion migration induced CoOx/Co redox effect,which is evidenced by the synchrotron X-ray absorption spectroscopy measurements.Interestingly,owing to the controllable ferroelectric switching dynamics of the BiFeO_(3) thin film,the magnetic coercive field of the Co thin film can be continuously and precisely tuned by controlling the ferroelectric polarization of the BiFeO_(3) thin film,and the manipulating speed of the voltage control of magnetism can be fast to 100 ns.This nonvolatile,stable,reversible,fast,and reproducible voltage control of magnetism shows great potential for designing low-power and high-speed spintronics.
基金supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,12005227,51790491,U2032150 and U1732148)the Users with Excellence Program of Hefei Science Center CAS(Nos.2019HSC-UE002,2020HSC-UE002,2020HSC-CIP013 and 2021HSC-UE002)+1 种基金the Postdoctoral Science Foundation of China(Nos.2020M682041,2020TQ0316 and 2019M662202)the National Key Research and Development Program of China(No.2019YFA0307900)。
文摘Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges.Herein,we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS2 bilayer with substitutional doping of Co ion,by introducing sulfur vacancy(V_(s))to modulate the interlayer electronic coupling.This strategy could transform the interlayer exchange interaction from antiferromagnetism(AFM)to ferromagnetism(FM),as revealed by the magnetic measurements.Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and Vs-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers,and also enhances the intralayer FM.Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional(2D)magnetic materials.
基金supported by the Fundamental Research Funds for the Central Universities(108-4115100092)the National Key Research and Development Program of China(2016YFA0300102 and 2017YFA0205004)+2 种基金the National Natural Science Foundation of China(11775224,11504358,11804324 and 52072102)the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(2018CXFX001)the Natural Science Research Projects for the Colleges and Universities of Anhui Province(KJ2018A0660)。
文摘Optical control of exotic properties in strongly correlated electron materials is very attractive owing to their potential applications in optical and electronic devices.Herein,we demonstrate a vertical heterojunction made of a correlated electron oxide thin film VO_(2) and a conductive 0.05 wt% Nb-doped TiO_(2) single crystal,whose metal-insulator transition(MIT)across the nanoscale heterointerface can be efficiently modulated by visible light irradiation.The magnitude of the MIT decreases from ~350 in the dark state to ~7 in the illuminated state,obeying a power law with respect to the light power density.The junction resistance is switched in a reversible and synchronous manner by turning light on and off.The optical tunability of it is also exponentially proportional to the light power density,and a 320-fold on/off ratio is achieved with an irradiance of 65.6 mW cm^(-2) below the MIT temperature.While the VO_(2) thin film is metallic above the MIT temperature,the optical tunability is remarkably weakened,with a one-fold change remaining under light illumination.These results are co-attributed to a net reduction(~15 meV)in the apparent barrier height and the photocarrier-injection-induced metallization of the VO_(2) heterointerface through a photovoltaic effect,which is induced by deep defect level transition upon the visible light irradiance at low temperature.Additionally,the optical tunability is minimal,resulting from the quite weak modulation of the already metallic band structure in the Schottky-type junction above the MIT temperature.This work enables a remotely optical scheme to manipulate the MIT,implying potential uncooled photodetection and photoswitch applications.
基金supported by the National Natural Science Foundation of China(51790491,51622209,and 21521001)the National Key Research and Development Program of China(2016YFA0300103 and 2015CB921201)。
文摘Modern electronics and electric power grids require high performance polymer-based dielectric nanocomposites.To realize large-scale applications,the energy density of nanocomposites needs to be further increased.Here,we demonstrate a remarkable improvement in energy density of poly(vinylidene fluoride)(PVDF)matrix upon the incorporation of high-k Bi_(4.2)K_(0.8)Fe_(2)O_(9+δ)(BKFO)nanobelts.High aspect ratio BKFO nanobelts can enhance the Young's moduli of the nanocomposites and increase the path tortuosity of electrical trees,which are favorable for increasing the breakdown strength of the system.Thus,the dielectric constant and breakdown strength increase simultaneously at a low volume fraction(0.35 vol%)of BKFO nanobelts,and an ultrahigh recoverable energy density of 25.4 J/cm^(3) is achieved.These results provide a strategy to develop high performance flexible high-energy-density devices.
