Heterostructures of van der Waals(vdW)ferromagnetic materials have become a focal point in research of lowdimensional spintronic devices.The current direction in spin valves is commonly perpendicular to the plane(CPP)...Heterostructures of van der Waals(vdW)ferromagnetic materials have become a focal point in research of lowdimensional spintronic devices.The current direction in spin valves is commonly perpendicular to the plane(CPP).However,the transport properties of the CPP mode remain largely unexplored.In this work,current-in-plane(CIP)mode and CPP mode for CrTe_(2) thin films are carefully studied.The temperature-dependent longitudinal resistance transitions from metallic(CIP)to semiconductor behavior(CPP),with the electrical resistivity of CPP increased by five orders of magnitude.More importantly,the transport properties of the CPP can be categorized into a single-gap tunneling-through model with the activation energy(Ea)of1.34 meV/gap at 300–150 K,the variable range hopping model with a linear negative magnetoresistance at 150–20 K,and weak localization region with a nonlinear magnetic resistance below 20 K.This study explores the vertical transport in CrTe_(2) materials for the first time,contributing to understand its unique properties and to pave the way for its potential in spin valve devices.展开更多
Coherent phonons have aroused considerable attention in condensed matter physics owing to their extraordinary capacity of reflecting and controlling the physical properties of matter.However,the investigation on the i...Coherent phonons have aroused considerable attention in condensed matter physics owing to their extraordinary capacity of reflecting and controlling the physical properties of matter.However,the investigation on the interaction between coherent phonons and other microscopic particles on the ultrafast timescale within topological systems continues to be an active and unresolved area.Here,we show the energy transfer of coherent optical phonons(COP)in Dirac semimetal PtTe2 thin films using ultrafast optical pump-probe spectroscopy.Specifically,the helicitydependent light-driven anisotropic COP signals disclose their direct connection with the light-excited anisotropic spinpolarized electrons via an angular momentum transfer.Furthermore,we observe the notable decreases in the COP oscillation frequency and the decay rate with increasing temperatures due to the anharmonic phonon-phonon scattering and electron-phonon scattering in the COP dissipation process,respectively.Our work paves the way for uncovering the coherent phonons in Dirac semimetals for the potential applications in optoelectronics and optospintronics.展开更多
基金the National Natural Science Foundation of China(Grant Nos.12241403 and 61974061)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20140054).
文摘Heterostructures of van der Waals(vdW)ferromagnetic materials have become a focal point in research of lowdimensional spintronic devices.The current direction in spin valves is commonly perpendicular to the plane(CPP).However,the transport properties of the CPP mode remain largely unexplored.In this work,current-in-plane(CIP)mode and CPP mode for CrTe_(2) thin films are carefully studied.The temperature-dependent longitudinal resistance transitions from metallic(CIP)to semiconductor behavior(CPP),with the electrical resistivity of CPP increased by five orders of magnitude.More importantly,the transport properties of the CPP can be categorized into a single-gap tunneling-through model with the activation energy(Ea)of1.34 meV/gap at 300–150 K,the variable range hopping model with a linear negative magnetoresistance at 150–20 K,and weak localization region with a nonlinear magnetic resistance below 20 K.This study explores the vertical transport in CrTe_(2) materials for the first time,contributing to understand its unique properties and to pave the way for its potential in spin valve devices.
基金supported by the National Key R&D Program of China(2022YFA1402404)the National Natural Science Foundation of China(12374104,52171230,T2394473,T2394470,62274085,61822403 and 11874120)the Fundamental Research Funds for the Central Universities(021014380225).
文摘Coherent phonons have aroused considerable attention in condensed matter physics owing to their extraordinary capacity of reflecting and controlling the physical properties of matter.However,the investigation on the interaction between coherent phonons and other microscopic particles on the ultrafast timescale within topological systems continues to be an active and unresolved area.Here,we show the energy transfer of coherent optical phonons(COP)in Dirac semimetal PtTe2 thin films using ultrafast optical pump-probe spectroscopy.Specifically,the helicitydependent light-driven anisotropic COP signals disclose their direct connection with the light-excited anisotropic spinpolarized electrons via an angular momentum transfer.Furthermore,we observe the notable decreases in the COP oscillation frequency and the decay rate with increasing temperatures due to the anharmonic phonon-phonon scattering and electron-phonon scattering in the COP dissipation process,respectively.Our work paves the way for uncovering the coherent phonons in Dirac semimetals for the potential applications in optoelectronics and optospintronics.
