Localization,one of the basic phenomena for wave transport,has been demonstrated to be an effective strategy to manipulate electronic,photonic,and acoustic properties of materials.Due to the wave nature of phonons,the...Localization,one of the basic phenomena for wave transport,has been demonstrated to be an effective strategy to manipulate electronic,photonic,and acoustic properties of materials.Due to the wave nature of phonons,the tuning of thermal properties through phonon localization would also be expected,which is beneficial to many applications such as thermoelectrics,electronics,and phononics.With the development of nanotechnology,nanostructures with characteristic length about ten nanometers can give rise to phonon localization,which has attracted considerable attention in recent years.This review aims to summarize recent advances with theoretical,simulative,and experimental studies toward understanding,prediction,and utilization of phonon localization in disordered nanostructures,focuses on the effect of phonon localization on thermal conductivity.Based on previous researches,perspectives regarding further researches to clarify this hecticinvestigated and immature topic and its exact effect on thermal transport are given.展开更多
Recently,the negative differential thermal resistance effect was discovered in a homojunction made of a negative thermal expansion material,which is very promising for realizing macroscopic thermal transistors.Similar...Recently,the negative differential thermal resistance effect was discovered in a homojunction made of a negative thermal expansion material,which is very promising for realizing macroscopic thermal transistors.Similar to the Monte Carlo phonon simulation to deal with grain boundaries,we introduce positive temperature-dependent interface thermal resistance in the modified Lorentz gas model and find negative differential thermal resistance effect.In the homojunction,we reproduce a pair of equivalent negative differential thermal resistance effects in different temperature gradient directions.In the heterojunction,we realize the unidirectional negative differential thermal resistance effect,and it is accompanied by the super thermal rectification effect.Using this new way to achieve high-performance thermal devices is a new direction,and will provide extensive reference and guidance for designing thermal devices.展开更多
We theoretically investigate the influence of off-resonant circularly polarized light field and perpendicular electric field on the quantum transport in a monolayer silicene-based normal/superconducting/normal junctio...We theoretically investigate the influence of off-resonant circularly polarized light field and perpendicular electric field on the quantum transport in a monolayer silicene-based normal/superconducting/normal junction.Owing to the tunable band structure of silicene,a pure crossed Andreev reflection process can be realized under the optical and electrical coaction.Moreover,a switch effect among the exclusive crossed Andreev reflection,the exclusive elastic cotunneling and the exclusive Andreev reflection,where the former two are the nonlocal transports and the third one is the local transport,can be obtained in our system by the modulation of the electric and light fields.In addition,the influence of the relevant parameters on the nonlocal and local transports is calculated and analyzed as well.展开更多
Introducing porosity with different degrees of disorder has been widely used to regulate thermal properties of materials, which generally results in decrease of thermal conductivity. We investigate the thermal conduct...Introducing porosity with different degrees of disorder has been widely used to regulate thermal properties of materials, which generally results in decrease of thermal conductivity. We investigate the thermal conductivity of porous metamaterials in the ballistic transport region by using the Lorentz gas model. It is found that the introduction of asymmetry and Gaussian disorder into porous metamaterials can lead to a strong enhancement of thermal conductivity. By dividing the transport process into ballistic transport, non-ballistic transport, and unsuccessful transport processes, we find that the enhancement of thermal conductivity originates from the significant increase ballistic transport ratio. The findings enhance the understanding of ballistic thermal transport in porous materials and may facilitate designs of high-performance porous thermal metamaterials.展开更多
An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the ...An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.展开更多
Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information.Here we experimentally demonstrate that three distinct domin...Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information.Here we experimentally demonstrate that three distinct dominated magneto-dynamic modes are excited simultaneously and coexist in a transversely magnetized ferromagnetic wire by the ferromagnetic resonance(FMR)technique.Besides the uniform FMR mode,the spin-wave well mode,the backward volume magnetostatic spin-wave mode,and the perpendicular standing spin-wave mode are experimentally observed and further confirmed with more detailed spatial profiles by micromagnetic simulation.Furthermore,our experimental approach can also access and reveal damping coefficients of these spin-wave modes,which provides essential information for development of magnonic devices in the future.展开更多
Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices.However,when flexible graphene nanosheets are assembled into macros...Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices.However,when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites,capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying,which greatly reduces the thermal conductivity of the composites.Herein,graphene nanosheets/aramid nanofiber(GNS/ANF)composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds andπ-πinteractions.The in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets,thereby creating a fast in-plane heat transfer channel.The composite films(GNS/ANF-60 wt%)with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity(146 W m^(−1)K^(−1))and tensile strength(207 MPa).The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones,showing promising applications in the thermal management of high-power electronic devices.展开更多
Reducing the thermal boundary resistance(TBR)is critical to enhance the thermal management efficiency and optimize the performance of electronic and thermoelectric devices.In this study,we employed non-equilibrium mol...Reducing the thermal boundary resistance(TBR)is critical to enhance the thermal management efficiency and optimize the performance of electronic and thermoelectric devices.In this study,we employed non-equilibrium molecular dynamics(NEMD)simulations using neuroevolution potential(NEP)machine learning models to investigate the impact of embedding nanoparticles in Si/Ge heterostructures on the TBR.Our results showed a significant reduction in the TBR.This was attributed to the enhanced phonon density of states matching via resonance,which promoted more efficient elastic phonon transport across the interface.However,this approach also led to a substantial increase in the bulk thermal resistance,highlighting a trade-off in which the overall heat dissipation is compromised.To address this,we investigated an alternative strategy in which a nanoparticle was positioned directly at the interface to modulate the interfacial modes,thereby improving the phonon transport efficiency without adversely affecting the bulk thermal properties.NEMD simulations validated this approach,showing a comparable TBR reduction,while mitigating the bulk thermal resistance increase observed with the resonance-based embedding method.This study offers valuable insights into resolving interfacial heat dissipation challenges and provides a balanced strategy for optimizing the thermal transport efficiency of nanoscale material systems.展开更多
Most of the reported observations are about the dynamic properties of individual domain-walls in magnetic nanowires,but the properties of multiple stripe-domains have rarely been investigated.Here,we demonstrate a sim...Most of the reported observations are about the dynamic properties of individual domain-walls in magnetic nanowires,but the properties of multiple stripe-domains have rarely been investigated.Here,we demonstrate a simple but efficient scenario for multiple domains injection in magnetic nanowires.The domain-chains(DCs),a cluster of multiple domains,can be dynamically generated with tunable static properties.It is found that the number of domains in a single DC can be dynamically adjusted by varying the frequency of microwave field(MF)and the period of spin-polarized current(SPC)intensity.The static properties of the DCs,i.e.,its length,spacing,and period between neighboring DCs,can be dynamically controlled by regulating the frequency of MF and the intensity of SPC.We have also discussed the possibility of using domain-chains as information carries,which provides a meaningful approach for flexible multi-bit information storage applications.展开更多
We numerically investigate the valley-polarized current in symmetric and asymmetric zigzag graphene nanoribbons(ZGNRs) by the adiabatic pump, and the effect of spatial symmetry is considered by introducing different p...We numerically investigate the valley-polarized current in symmetric and asymmetric zigzag graphene nanoribbons(ZGNRs) by the adiabatic pump, and the effect of spatial symmetry is considered by introducing different pumping regions. It is found that pumping potentials with the symmetry Vp(x,y) = Vp(-x,y)can generate the largest valleypolarized current. The valley-polarized currents I13~L with the pumping potential symmetry Vp(x,y) =Vp(x,-y,) and I14~L with Vp(x,y) = Vp(-x,-y) of symmetric ZGNRs are much smaller than those of asymmetric ZGNRs. We also find I13~L and I14~L of symmetric ZGNRs decrease and increase with the increasing pumping amplitude, respectively. Moreover, the dephasing effect from the electron-phonon coupling within the Buttiker dephasing scheme is introduced. The valley-polarized current of the symmetric ZGNRs with Vp(x,y)= Vp(x,-y) increases with the increase of the dephasing strength while that with Vp(x,y) = Vp(-x,-y) decreases as the dephasing strength increases.展开更多
Super-resolution optical fluctuation imaging is dependent on the blinking frequency of fluorophores.Consequently,improvement of the photoluminescence(PL)blink frequency is important.This is achieved for 3C–SiC nanocr...Super-resolution optical fluctuation imaging is dependent on the blinking frequency of fluorophores.Consequently,improvement of the photoluminescence(PL)blink frequency is important.This is achieved for 3C–SiC nanocrystals(NCs)by simply increasing the excitation power.Using an excitation of 488 nm with powers of 5μW to 50μW,individual 3C–SiC NC always exhibits PL blinking with a short on-state sojourn time(<0.1 s).A fast Fourier transform method is exploited to determine the PL switching frequency.It is found that the frequency of the bright state increases from 2 Hz to 20 Hz as the excitation power increases from 5μW to 50μW,which is explained by the Auger photonionization model.展开更多
In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field(Hex) and strength(-Jiec) in synthetic antiferromagnetic(SAF) structure of [Pt(0.6)/Co(0.6)]2/Ru(tRu)/[Co(0.6...In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field(Hex) and strength(-Jiec) in synthetic antiferromagnetic(SAF) structure of [Pt(0.6)/Co(0.6)]2/Ru(tRu)/[Co(0.6)/Pt(0.6)]4multilayers with perpendicular anisotropy. Depending on the thickness of the spacing ruthenium(Ru) layer, the observed interlayer exchange coupling can be either ferromagnetic or antiferromagnetic. The Hexwere studied by measuring the magnetization hysteresis loops in the temperature range from 100 K to 700 K as well as the theoretical calculation of the-Jiec. It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The Hexexhibits either a linear or a non-linear dependence on the temperature for different thickness of Ru. Furthermore, our SAF multilayers show a high thermal stability even up to 600 K(Hex= 3.19 kOe,-Jiec= 1.97 erg/cm~2 for tRu=0.6 nm, the unit 1 Oe = 79.5775 A·m-1), which was higher than the previous studies.展开更多
Among the layered two-dimensional ferromagnetic materials(2D FMs),due to a relatively high T_(C),the van der Waals(vdW)Fe_(3)GeTe_(2)(FGT)crystal is of great importance for investigating its distinct magnetic properti...Among the layered two-dimensional ferromagnetic materials(2D FMs),due to a relatively high T_(C),the van der Waals(vdW)Fe_(3)GeTe_(2)(FGT)crystal is of great importance for investigating its distinct magnetic properties.Here,we have carried out static and dynamic magnetization measurements of the FGT crystal with a Curie temperature TC≈204 K.The M-H hysteresis loops with in-plane and out-of-plane orientations show that FGT has a strong perpendicular magnetic anisotropy with the easy axis along its c-axis.Moreover,we have calculated the uniaxial magnetic anisotropy constant(K_(1))from the SQUID measurements.The dynamic magnetic properties of FGT have been probed by utilizing the high sensitivity electron-spin-resonance(ESR)spectrometer at cryogenic temperatures.Based on an approximation of single magnetic domain mode,the K_(1)and the effective damping constant(αeff)have also been determined from the out-of-plane angular dependence of ferromagnetic resonance(FMR)spectra obtained at the temperature range of 185 K to T_(C).We have found large magnetic damping with the effective damping constantαeff~0.58 along with a broad linewidth(ΔH_(pp)>1000 Oe at 9.48 GHz,H||c-axis).Our results provide useful dynamics information for the development of FGT-based spintronic devices.展开更多
Inspired by the recent experimental progress in noisy kicked rotor systems,we investigate the effect of temporal disorder or quasi-periodicity in one-dimensional kicked lattices with pulsed on-site potential.We found ...Inspired by the recent experimental progress in noisy kicked rotor systems,we investigate the effect of temporal disorder or quasi-periodicity in one-dimensional kicked lattices with pulsed on-site potential.We found that,unlike the spatial disorder or quasi-periodicity which usually leads to localization,the effect of the temporal one is more complex and depends on the spatial configuration.If the kicked on-site potential is periodic in real space,then the wave packet will stay diffusive in the presence of temporal disorder or quasi-periodicity.On the other hand,if the kicked on-site potential is spatially quasi-periodic,then the temporal disorder or quasi-periodicity may lead to a shift of the transition point of the dynamical localization and destroy the dynamical localization in a certain parameter range.The results we obtained can be readily tested by experiments and may help us better understand the dynamical localization.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11975125,11890703,and 21803031)the Natural Science Foundation of the Jiangsu Higher Education Institution of China(Grant No.18KJB150022)+1 种基金Postdoctoral Research Funding Program of Jiangsu,China(Grant No.2020Z163)China Postdoctoral Science Foundation(Grant No.2020M671533)。
文摘Localization,one of the basic phenomena for wave transport,has been demonstrated to be an effective strategy to manipulate electronic,photonic,and acoustic properties of materials.Due to the wave nature of phonons,the tuning of thermal properties through phonon localization would also be expected,which is beneficial to many applications such as thermoelectrics,electronics,and phononics.With the development of nanotechnology,nanostructures with characteristic length about ten nanometers can give rise to phonon localization,which has attracted considerable attention in recent years.This review aims to summarize recent advances with theoretical,simulative,and experimental studies toward understanding,prediction,and utilization of phonon localization in disordered nanostructures,focuses on the effect of phonon localization on thermal conductivity.Based on previous researches,perspectives regarding further researches to clarify this hecticinvestigated and immature topic and its exact effect on thermal transport are given.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11975125 and 21803031)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX201229)the Natural Science Foundation of the Jiangsu Higher Education Institution of China(Grant No.18KJB150022).
文摘Recently,the negative differential thermal resistance effect was discovered in a homojunction made of a negative thermal expansion material,which is very promising for realizing macroscopic thermal transistors.Similar to the Monte Carlo phonon simulation to deal with grain boundaries,we introduce positive temperature-dependent interface thermal resistance in the modified Lorentz gas model and find negative differential thermal resistance effect.In the homojunction,we reproduce a pair of equivalent negative differential thermal resistance effects in different temperature gradient directions.In the heterojunction,we realize the unidirectional negative differential thermal resistance effect,and it is accompanied by the super thermal rectification effect.Using this new way to achieve high-performance thermal devices is a new direction,and will provide extensive reference and guidance for designing thermal devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504084 and 11647164)the Natural Science Foundation for Colleges and Universities in Jiangsu Province,China(Grant Nos.18KJB140005,17KJD170004,and 16KJB140008)
文摘We theoretically investigate the influence of off-resonant circularly polarized light field and perpendicular electric field on the quantum transport in a monolayer silicene-based normal/superconducting/normal junction.Owing to the tunable band structure of silicene,a pure crossed Andreev reflection process can be realized under the optical and electrical coaction.Moreover,a switch effect among the exclusive crossed Andreev reflection,the exclusive elastic cotunneling and the exclusive Andreev reflection,where the former two are the nonlocal transports and the third one is the local transport,can be obtained in our system by the modulation of the electric and light fields.In addition,the influence of the relevant parameters on the nonlocal and local transports is calculated and analyzed as well.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11975125 and 11890703)the Department of Science and Technology of Jiangsu Province (Grant No. BK20220032)。
文摘Introducing porosity with different degrees of disorder has been widely used to regulate thermal properties of materials, which generally results in decrease of thermal conductivity. We investigate the thermal conductivity of porous metamaterials in the ballistic transport region by using the Lorentz gas model. It is found that the introduction of asymmetry and Gaussian disorder into porous metamaterials can lead to a strong enhancement of thermal conductivity. By dividing the transport process into ballistic transport, non-ballistic transport, and unsuccessful transport processes, we find that the enhancement of thermal conductivity originates from the significant increase ballistic transport ratio. The findings enhance the understanding of ballistic thermal transport in porous materials and may facilitate designs of high-performance porous thermal metamaterials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074189,11704191,11774160,and 61427812)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20192006 and BK20211144)the Postdoctoral Research Funding Program of Jiangsu Province,China(Grant No.2021K503C)。
文摘An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.
基金Supported by the National Key Research and Development Program of China(Grant No.2016YFA0300803)the Open Research Fund of Jiangsu Provincial Key Laboratory for Nanotechnology,the National Natural Science Foundation of China(Grant Nos.11774150 and 11704191)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20171026 and BK20170627).
文摘Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information.Here we experimentally demonstrate that three distinct dominated magneto-dynamic modes are excited simultaneously and coexist in a transversely magnetized ferromagnetic wire by the ferromagnetic resonance(FMR)technique.Besides the uniform FMR mode,the spin-wave well mode,the backward volume magnetostatic spin-wave mode,and the perpendicular standing spin-wave mode are experimentally observed and further confirmed with more detailed spatial profiles by micromagnetic simulation.Furthermore,our experimental approach can also access and reveal damping coefficients of these spin-wave modes,which provides essential information for development of magnonic devices in the future.
基金the National Natural Science Foundation of China(No.51972162).
文摘Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic devices.However,when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites,capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying,which greatly reduces the thermal conductivity of the composites.Herein,graphene nanosheets/aramid nanofiber(GNS/ANF)composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds andπ-πinteractions.The in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets,thereby creating a fast in-plane heat transfer channel.The composite films(GNS/ANF-60 wt%)with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity(146 W m^(−1)K^(−1))and tensile strength(207 MPa).The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones,showing promising applications in the thermal management of high-power electronic devices.
基金supported in part by the National Natural Science Foundation of China(Grant No.12105242)the Yunnan Fundamental Research Project(Grant Nos.202201AT070161 and 202301AW070006)+2 种基金the Department of Science and Technology of Jiangsu Province(Grant No.BK20231279)the financial support provided by the Xing Dian Talent Programthe support provided by the Graduate Scientific Research and Innovation Fund of Yunnan University(KC-23234635)。
文摘Reducing the thermal boundary resistance(TBR)is critical to enhance the thermal management efficiency and optimize the performance of electronic and thermoelectric devices.In this study,we employed non-equilibrium molecular dynamics(NEMD)simulations using neuroevolution potential(NEP)machine learning models to investigate the impact of embedding nanoparticles in Si/Ge heterostructures on the TBR.Our results showed a significant reduction in the TBR.This was attributed to the enhanced phonon density of states matching via resonance,which promoted more efficient elastic phonon transport across the interface.However,this approach also led to a substantial increase in the bulk thermal resistance,highlighting a trade-off in which the overall heat dissipation is compromised.To address this,we investigated an alternative strategy in which a nanoparticle was positioned directly at the interface to modulate the interfacial modes,thereby improving the phonon transport efficiency without adversely affecting the bulk thermal properties.NEMD simulations validated this approach,showing a comparable TBR reduction,while mitigating the bulk thermal resistance increase observed with the resonance-based embedding method.This study offers valuable insights into resolving interfacial heat dissipation challenges and provides a balanced strategy for optimizing the thermal transport efficiency of nanoscale material systems.
基金Project supported by the National Natural Science Foundation of China(Grant No.11704191)the Jiangsu Specially-Appointed Professor,the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20171026)the Six-Talent Peaks Project in Jiangsu Province,China(Grant No.XYDXX-038)
文摘Most of the reported observations are about the dynamic properties of individual domain-walls in magnetic nanowires,but the properties of multiple stripe-domains have rarely been investigated.Here,we demonstrate a simple but efficient scenario for multiple domains injection in magnetic nanowires.The domain-chains(DCs),a cluster of multiple domains,can be dynamically generated with tunable static properties.It is found that the number of domains in a single DC can be dynamically adjusted by varying the frequency of microwave field(MF)and the period of spin-polarized current(SPC)intensity.The static properties of the DCs,i.e.,its length,spacing,and period between neighboring DCs,can be dynamically controlled by regulating the frequency of MF and the intensity of SPC.We have also discussed the possibility of using domain-chains as information carries,which provides a meaningful approach for flexible multi-bit information storage applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704190,11874221,and 11504240)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20171030)
文摘We numerically investigate the valley-polarized current in symmetric and asymmetric zigzag graphene nanoribbons(ZGNRs) by the adiabatic pump, and the effect of spatial symmetry is considered by introducing different pumping regions. It is found that pumping potentials with the symmetry Vp(x,y) = Vp(-x,y)can generate the largest valleypolarized current. The valley-polarized currents I13~L with the pumping potential symmetry Vp(x,y) =Vp(x,-y,) and I14~L with Vp(x,y) = Vp(-x,-y) of symmetric ZGNRs are much smaller than those of asymmetric ZGNRs. We also find I13~L and I14~L of symmetric ZGNRs decrease and increase with the increasing pumping amplitude, respectively. Moreover, the dephasing effect from the electron-phonon coupling within the Buttiker dephasing scheme is introduced. The valley-polarized current of the symmetric ZGNRs with Vp(x,y)= Vp(x,-y) increases with the increase of the dephasing strength while that with Vp(x,y) = Vp(-x,-y) decreases as the dephasing strength increases.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11604155,11604147,and 51702379)China Postdoctoral Science Foundation(Grant Nos.2016M600428 and 2017T100386)the Planned Projects for Postdoctoral Research Funds of China(Grant No.1601023A)
文摘Super-resolution optical fluctuation imaging is dependent on the blinking frequency of fluorophores.Consequently,improvement of the photoluminescence(PL)blink frequency is important.This is achieved for 3C–SiC nanocrystals(NCs)by simply increasing the excitation power.Using an excitation of 488 nm with powers of 5μW to 50μW,individual 3C–SiC NC always exhibits PL blinking with a short on-state sojourn time(<0.1 s).A fast Fourier transform method is exploited to determine the PL switching frequency.It is found that the frequency of the bright state increases from 2 Hz to 20 Hz as the excitation power increases from 5μW to 50μW,which is explained by the Auger photonionization model.
基金Project supported by the National Natural Science Foundation of China(Grant No.11704191)the Jiangsu Specially-Appointed Professor,the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20171026)the Six-Talent Peaks Project in Jiangsu Province,China(Grant No.XYDXX-038)
文摘In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field(Hex) and strength(-Jiec) in synthetic antiferromagnetic(SAF) structure of [Pt(0.6)/Co(0.6)]2/Ru(tRu)/[Co(0.6)/Pt(0.6)]4multilayers with perpendicular anisotropy. Depending on the thickness of the spacing ruthenium(Ru) layer, the observed interlayer exchange coupling can be either ferromagnetic or antiferromagnetic. The Hexwere studied by measuring the magnetization hysteresis loops in the temperature range from 100 K to 700 K as well as the theoretical calculation of the-Jiec. It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The Hexexhibits either a linear or a non-linear dependence on the temperature for different thickness of Ru. Furthermore, our SAF multilayers show a high thermal stability even up to 600 K(Hex= 3.19 kOe,-Jiec= 1.97 erg/cm~2 for tRu=0.6 nm, the unit 1 Oe = 79.5775 A·m-1), which was higher than the previous studies.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0300803)the National Natural Science Foundation of China(Grant Nos.11774150,12074178,61427812,11774160,61805116,and 61271077)the Natural Science Foundation of Jiangsu Province of China(Grant Nos.BK20192006,BK20180056,and BK20200307).
文摘Among the layered two-dimensional ferromagnetic materials(2D FMs),due to a relatively high T_(C),the van der Waals(vdW)Fe_(3)GeTe_(2)(FGT)crystal is of great importance for investigating its distinct magnetic properties.Here,we have carried out static and dynamic magnetization measurements of the FGT crystal with a Curie temperature TC≈204 K.The M-H hysteresis loops with in-plane and out-of-plane orientations show that FGT has a strong perpendicular magnetic anisotropy with the easy axis along its c-axis.Moreover,we have calculated the uniaxial magnetic anisotropy constant(K_(1))from the SQUID measurements.The dynamic magnetic properties of FGT have been probed by utilizing the high sensitivity electron-spin-resonance(ESR)spectrometer at cryogenic temperatures.Based on an approximation of single magnetic domain mode,the K_(1)and the effective damping constant(αeff)have also been determined from the out-of-plane angular dependence of ferromagnetic resonance(FMR)spectra obtained at the temperature range of 185 K to T_(C).We have found large magnetic damping with the effective damping constantαeff~0.58 along with a broad linewidth(ΔH_(pp)>1000 Oe at 9.48 GHz,H||c-axis).Our results provide useful dynamics information for the development of FGT-based spintronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.11575087)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20160094)
文摘Inspired by the recent experimental progress in noisy kicked rotor systems,we investigate the effect of temporal disorder or quasi-periodicity in one-dimensional kicked lattices with pulsed on-site potential.We found that,unlike the spatial disorder or quasi-periodicity which usually leads to localization,the effect of the temporal one is more complex and depends on the spatial configuration.If the kicked on-site potential is periodic in real space,then the wave packet will stay diffusive in the presence of temporal disorder or quasi-periodicity.On the other hand,if the kicked on-site potential is spatially quasi-periodic,then the temporal disorder or quasi-periodicity may lead to a shift of the transition point of the dynamical localization and destroy the dynamical localization in a certain parameter range.The results we obtained can be readily tested by experiments and may help us better understand the dynamical localization.
