查看更多>>摘要：Recently,giant intrinsic anomalous Hall effect(AHE)has been observed in the materials with kagome lattice.Here,we systematically investigate the influence of high pressure on the AHE in the ferromagnet LiMn6Sn6 with clean Mn kagome lattice.Our in situ high-pressure Raman spectroscopy indicates that the crystal structure of LiMn6Sn6 maintains a hexagonal phase under high pressures up to 8.51 GPa.The anomalous Hall conductivity(AHC)σAxy remains around 150 Ω-1·cm-1,dominated by the intrinsic mechanism.Combined with theoretical calculations,our results indicate that the stable AHE under pressure in LiMn6Sn6 originates from the robust electronic and magnetic structure.
查看更多>>摘要：Quantum anomalous Hall(QAH)insulators have highly potential applications in spintronic device.However,available candidates with tunable Chern numbers and high working temperature are quite rare.Here,we predict a 1T-PrN2 monolayer as a stable QAH insulator with high magnetic transition temperature of above 600 K and tunable high Chern numbers of C=±3 from first-principles calculations.Without spin-orbit coupling(SOC),the 1T-PrN2 monolayer is predicted to be a p-state Dirac half metal with high Fermi velocity.Rich topological phases depending on magnetization directions can be found when the SOC is considered.The QAH effect with periodical changes of Chern number(±1)can be produced when the magnetic moment breaks all twofold rotational symmetries in the xy plane.The critical state can be identified as Weyl half semimetals.When the magnetization direction is parallel to the z-axis,the system exhibits high Chern number QAH effect with C=±3.Our work provides a new material for exploring novel QAH effect and developing high-performance topological devices.
查看更多>>摘要：Based on first-principles calculations,we systematically study the stacking energy and interlayer magnetic interaction of the heterobilayer composed of CrI3 and CrSe2 monolayers.It is found that the stacking order plays a crucial role in the interlayer magnetic coupling.Among all possible stacking structures,the AA-stacking is the most stable heterostructure,exhibiting interlayer antiferromagnetic interactions.Interestingly,the interlayer magnetic interaction can be effectively tuned by biaxial strain.A 4.3％compressive strain would result in a ferromagnetic interlayer interaction in all stacking orders.These results reveal the magnetic properties of CrI3/CrSe2 heterostructure,which is expected to be applied to spintronic devices.
查看更多>>摘要：Understanding the doping evolution from a Mott insulator to a superconductor probably holds the key to resolve the mystery of unconventional superconductivity in copper oxides.To elucidate the evolution of the electronic state starting from the Mott insulator,we dose the surface of the parent phase Ca2CuO2Cl2 by depositing Rb atoms,which are supposed to donate electrons to the CuO2 planes underneath.We successfully achieved the Rb sub-monolayer thin films in forming the square lattice.The scanning tunneling microscopy or spectroscopy measurements on the surface show that the Fermi energy is pinned within the Mott gap but close to the edge of the charge transfer band.In addition,an in-gap state appears at the bottom of the upper Hubbard band(UHB),and the Mott gap will be significantly diminished.Combined with the Cl defect and the Rb adatom/cluster results,the electron doping is likely to increase the spectra weight of the UHB for the double occupancy.Our results provide information to understand the electron doping to the parent compound of cuprates.
查看更多>>摘要：The recent discovery of possible high temperature superconductivity in single crystals of La3Ni2O7 under pressure renews the interest in research on nickelates.The density functional theory calculations reveal that both dz2 and dx2-y2 orbitals are active,which suggests a minimal two-orbital model to capture the low-energy physics of this system.In this work,we study a bilayer two-orbital t-J model within multiband Gutzwiller approximation,and discuss the magnetism as well as the superconductivity over a wide range of the hole doping.Owing to the inter-orbital super-exchange process between dz2 and dx2-y2 orbitals,the induced ferromagnetic coupling within layers competes with the conventional antiferromagnetic coupling,and leads to complicated hole doping dependence for the magnetic properties in the system.With increasing hole doping,the system transfers to A-type antiferromagnetic state from the starting G-type antiferromagnetic(G-AFM)state.We also find the inter-layer superconducting pairing of dx2-y2 orbitals dominates due to the large hopping parameter of dz2 along the vertical inter-layer bonds and significant Hund's coupling between dz2 and dx2-y2 orbitals.Meanwhile,the G-AFM state and superconductivity state can coexist in the low hole doping regime.To take account of the pressure,we also analyze the impacts of inter-layer hopping amplitude on the system properties.
查看更多>>摘要：Electrical control of magnetism in van der Waals semiconductors is a promising step towards development of two-dimensional spintronic devices with ultralow power consumption for processing and storing information.Here,we propose a design for two-dimensional van der Waals heterostructures(vdWHs)that can host ferroelec-tricity and ferromagnetism simultaneously under hole doping.By contacting an InSe monolayer and forming an InSe/In2Se3 vdWH,the switchable built-in electric field from the reversible out-of-plane polarization enables robust control of the band alignment.Furthermore,switching between the two ferroelectric states(P↑ and P↓)of hole-doped In2Se3 with an external electric field can interchange the ON and OFF states of the nonvolatile magnetism.More interestingly,doping concentration and strain can effectively tune the magnetic moment and polarization energy.Therefore,this provides a platform for realizing multiferroics in ferroelectric heterostructures,showing great potential for use in nonvolatile memories and ferroelectric field-effect transistors.
查看更多>>摘要：Magnetic domain wall(DW),as one of the promising information carriers in spintronic devices,have been widely investigated owing to its nonlinear dynamics and tunable properties.Here,we theoretically and numerically demonstrate the DW dynamics driven by the synergistic interaction between current-induced spin-transfer torque(STT)and voltage-controlled strain gradient(VCSG)in multiferroic heterostructures.Through electromechanical and micromagnetic simulations,we show that a desirable strain gradient can be created and it further modulates the equilibrium position and velocity of the current-driven DW motion.Meanwhile,an analytical Thiele's model is developed to describe the steady motion of DW and the analytical results are quite consistent with the simulation data.Finally,we find that this combination effect can be leveraged to design DW-based biological neurons where the synergistic interaction between STT and VCSG-driven DW motion as integrating and leaking motivates mimicking leaky-integrate-and-fire(LIF)and self-reset function.Importantly,the firing response of the LIF neuron can be efficiently modulated,facilitating the exploration of tunable activation function generators,which can further help improve the computational capability of the neuromorphic system.
查看更多>>摘要：Rare-earth-free Mn-based binary alloy L10-MnAl with bulk perpendicular magnetic anisotropy(PMA)holds promise for high-performance magnetic random access memory(MRAM)devices driven by spin-orbit torque(SOT).However,the lattice-mismatch issue makes it challenging to place conventional spin current sources,such as heavy metals,between L10-MnAl layers and substrates.In this work,we propose a solution by using the B2-CoGa alloy as the spin current source.The lattice-matching enables high-quality epitaxial growth of 2-nm-thick L10-MnAl on B2-CoGa,and the L10-MnAl exhibits a large PMA constant of 1.04 × 106 J/m3.Subsequently,the considerable spin Hall effect in B2-CoGa enables the achievement of SOT-induced deterministic magnetization switching.Moreover,we quantitatively determine the SOT efficiency in the bilayer.Furthermore,we design an L10-MnAl/B2-CoGa/Co2MnGa structure to achieve field-free magnetic switching.Our results provide valuable insights for achieving high-performance SOT-MRAM devices based on L10-MnAl alloy.
查看更多>>摘要：Controlling collective electronic states hold great promise for development of innovative devices.Here,we experimentally detect the modification of the charge density wave(CDW)phase transition within a 1T-TaS2 layer in a WS2/1T-TaS2 heterostructure using time-resolved ultrafast spectroscopy.Laser-induced charge transfer doping strongly suppresses the commensurate CDW phase,which results in a significant decrease in both the phase transition temperature(Tc)and phase transition stiffness.We interpret the phenomenon that photo-induced hole doping,when surpassing a critical threshold value of～1018cm-3,sharply decreases the phase transition energy barrier.Our results provide new insights into controlling the CDW phase transition,paving the way for optical-controlled novel devices based on CDW materials.
查看更多>>摘要：Compared with conventional solid-state electrolytes,halide solid-state electrolytes have several advantages such as a wider electrochemical window,better compatibility with oxide cathode materials,improved air stability,and easier preparation conditions making them conductive to industrial production.We concentrate on a typical halide solid-state electrolyte,Li3InCl6,predict the most stable structure after doping with Br,F,and Ga by using the Alloy Theoretic Automated Toolkit based on first-principles calculations,and verify the accuracy of the pre-diction model.To investigate the potential of three equivalently doped ground state configurations of Li3InCl6 as solid-state electrolytes for all-solid-state lithium-ion batteries,their specific properties such as crystal structure,band gap,convex packing energy,electrochemical stability window,and lithium-ion conductivity are computa-tionally analyzed using first-principles calculations.After a comprehensive evaluation,it is determined that the F-doped ground state configuration Li3InCl2.5F3.5 exhibits better thermal stability,wider electrochemical stabil-ity window,and better lithium ion conductivity(1.80mS·cm-1 at room temperature).Therefore,Li3InCl2.5F3.5 has the potential to be used in the field of all-solid-state lithium-ion batteries as a new type of halide electrolyte.
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