查看更多>>摘要：While density functional theory(DFT)serves as a prevalent computational approach in electronic structure calculations,its computational demands and scalability limitations persist.Recently,leveraging neural networks to parameterize the Kohn-Sham DFT Hamiltonian has emerged as a promising avenue for accelerating electronic structure computations.Despite advancements,challenges such as the necessity for computing extensive DFT training data to explore each new system and the complexity of establishing accurate machine learning models for multi-elemental materials still exist.Addressing these hurdles,this study introduces a universal electronic Hamiltonian model trained on Hamiltonian matrices obtained from first-principles DFT calculations of nearly all crystal structures on the Materials Project.We demonstrate its generality in predicting electronic structures across the whole periodic table,including complex multi-elemental systems,solid-state electrolytes,Moiré twisted bilayer heterostructure,and metal-organic frameworks.Moreover,we utilize the universal model to conduct high-throughput calculations of electronic structures for crystals in GNoME datasets,identifying 3940 crystals with direct band gaps and 5109 crystals with flat bands.By offering a reliable efficient framework for computing electronic properties,this universal Hamiltonian model lays the groundwork for advancements in diverse fields,such as easily providing a huge data set of electronic structures and also making the materials design across the whole periodic table possible.
查看更多>>摘要：The reliance on spin-orbit coupling or strong magnetic fields has always posed significant challenges for the mass production and even laboratory realization of most topological materials.Valley-based topological zero-line modes have attracted widespread attention due to their substantial advantage of being initially realizable with just an external electric field.However,the uncontrollable nature of electrode alignment and precise fabrication has greatly hindered the advancement in this field.By utilizing minimally twisted bilayer graphene and introducing exchange fields from magnetic substrates,we successfully realize a spin-resolved,electrode-free topological zero-line mode.Further integration of electrodes that do not require alignment considerations significantly enhances the tunability of the system's band structure.Our approach offers a promising new support for the dazzling potential of topological zero-line mode in the realm of low-energy-consumption electronics.
查看更多>>摘要：We present a study on inelastic thermoelectric devices,wherein charge currents and electronic and phononic heat currents are intricately interconnected.The employment of double quantum dots in conjunction with a phonon reservoir positions them as promising candidates for quantum thermoelectric diodes and transistors.We illustrate that quantum coherence yields significant charge and Seebeck rectification effects.It is worth noting that,while the thermal transistor effect is observable in the linear response regime,especially when phonon-assisted inelastic processes dominate the transport,quantum coherence does not enhance thermal amplification.Our work may provide valuable insights for the optimization of inelastic thermoelectric devices.
查看更多>>摘要：We systematically investigate in-plane transport properties of ternary chalcogenide Bi2Rh3Se2.Upon rotating the magnetic field within the plane of the sample,one can distinctly detect the presence of both planar Hall resistance and anisotropic longitudinal resistance,and the phenomena appeared are precisely described by the theoretical formulation of the planar Hall effect(PHE).In addition,anisotropic orbital magnetoresistance rather than topologically nontrivial chiral anomalies dominates the PHE in Bi2Rh3Se2.The finding not only provides another platform for understanding the mechanism of PHE,but could also be beneficial for future planar Hall sensors based on two-dimensional materials.
查看更多>>摘要：The rattling mode,an anharmonic vibrational phonon,is widely recognized as a critical factor in the emergence of superconductivity in caged materials.Here,we present a counterexample in a filled-skutterudite superconductor BaxIr4Sb12(x=0.8,0.9,1.0),synthesized via a high-pressure route.Transport measurements down to liquid 3He temperatures reveal a transition temperature(Tc)of 1.2 K and an upper critical field(Hc2)of 1.3 T.Unlike other superconductors with caged structures,the BaxIr4X12(X=P,As,Sb)family exhibits a monotonic decreasing Tc with the enhancement of the rattling mode,as indicated by fitting the Bloch-Grüneisen formula.Theoretical analysis suggests that electron doping from Ba transforms the direct bandgap IrSb3 into a metal,with the Fermi surface dominated by the hybridization of Ir 5d and Sb 5p orbitals.Our findings of decoupled rattling modes and superconductivity distinguish the BaxIr4Sb12 family from other caged superconductors,warranting further exploration into the underlying mechanism.
查看更多>>摘要：This review provides a comprehensive overview of current research on the structural,electronic,and magnetic characteristics of the recently discovered high-temperature superconductor La3Ni2O7 under high pressures.We present the experimental results for synthesizing and characterizing this material,derived from measurements of transport,thermodynamics,and various spectroscopic techniques,and discuss their physical implications.We also explore theoretical models proposed to describe the electronic structures and superconducting pairing symmetry in La3Ni2O7,highlighting the intricate interplay between electronic correlations and magnetic interactions.Despite these advances,challenges remain in growing high-quality samples free of extrinsic phases and oxygen deficiencies and in developing reliable measurement tools for determining diamagnetism and other physical quantities under high pressures.Further investigations in these areas are essential to deepening our understanding of the physical properties of La3Ni2O7 and unlocking its superconducting pairing mechanism.
查看更多>>摘要：The 0.98(K0.5Na0.5)NbO3-0.02Ba(Nb0.5Co0.5)O3-δ ceramics with doped Ba2+and Co2+ions are fabricated,and the impacts of the thermal process are studied.Compared with the rapidly cooled(RC)sample,the slowly cooled(SC)sample possesses superior dielectric and ferroelectric properties,and an 11K higher ferroelectric-paraelectric phase transition temperature,which can be attributed to the structural characteristics such as the grain size and the degree of anisotropy.Heat treatment can reversibly modulate the content of the oxygen vacancies,and in turn the ferroelectric hysteresis loops of the samples.Finally,robust and tunable ferroelectric property is achieved in SC samples with good structural integrity.
查看更多>>摘要：The pursuit of high-energy cathode materials has been focused on raising the charging cutoff voltage of nickel(Ni)-rich layered oxide cathode such as LiNi0.8Co0.1Mn0.1O2(NCM811).However,the NCM811 suffers from rapid capacity fading upon cycling at cutoff voltage higher than 4.5 V,owing to their structural degradation and labile surface reactivity.Surface-coating with solid electrolytes has been recognized as an effective method to mitigate the performance failure of NCM811 at high voltage.Herein,the nano-sized Li6.4La3Ta0.6Zr1.4O12(LLZTO)is uniformly coated on the surface of single-crystal NCM811 particles,accompanied with the long-range Ta5+diffusion into the transition metal layer of NCM811 lattice.It is revealed that the LLZTO coating can not only inhibit the surface reactions of NCM811 with liquid electrolytes but also play an important role in suppressing the bulk microcracking within the NCM811 particles.The incorporation of Ta5+ion expands the lattice spacing and thereby improves the homogeneity of the Li+diffusion in the single-crystal NCM811,which alleviates the mechanical strain and intragranular cracks caused by nonuniform phases-transformation at high charging voltage.The synergy of surface protection and structural stabilization realized by LLZTO coating enables the NCM811-based lithium batteries to achieve a remarkable electrochemical performance.Typically,LLZTO coated NCM811 delivers a high reversible specific capacity of 202.1 mAh·g-1 with an excellent capacity retention as high as 70％over 1000 cycles upon charging to 4.5 V at 1 C.
查看更多>>摘要：Compared to commercial lithium-ion batteries,all-solid-state batteries can greatly increase the energy density,safety,and cycle life of batteries.The development of solid-state electrolyte with high lithium-ion conductivity and wide electrochemical window is the key for all-solid-state batteries.In this work,we report on the achievement of high ionic conductivity in the PAN/LiClO4/BaTiO3 composite solid electrolyte(CSE)prepared by solution casting method.Our experimental results show that the PAN-based composite polymer electrolyte with 5wt％BaTiO3 possesses a high room-temperature lithium-ion conductivity(9.85 × 10-4 S·cm-1),high lithium-ion trans-fer number(0.63),wide electrochemical window(4.9 V vs Li+/Li).The Li|Li symmetric battery assembled with 5wt％BaTiO3 can be stably circulated for 800h at 0.1mA·cm-2,and the LiFePO4|CSE|Li battery maintains a capacity retention of 86.2％after 50 cycles at a rate of 0.3 C.The influence of BaTiO3 ceramic powder on the properties of PAN-based polymer electrolytes is analyzed.Our results provide a new avenue for future research in the all-solid-state lithium battery technology.
查看更多>>摘要：Using micromagnetic simulations,we demonstrate the tilted perpendicular anisotropy-induced spin-orbit ratchet effect.In spin-orbit torque(SOT)-induced magnetization switching,the critical currents required to switch between the two magnetization states(upward and downward magnetization)are asymmetric.In addi-tion,in the nanowire structure,tilted anisotropy induces formation of tilted domain walls(DWs).The tilted DWs exhibit a ratchet behavior during motion.The ratchet effect during switching and DW motions can be tuned by changing the current direction with respect to the tilting direction of anisotropy.The ratchet motion of the DWs can be used to mimic the leaky-integrate-fire function of a biological neuron,especially the asymmetric property of the"potential"and"reset"processes.Our results provide a full understanding of the influence of tilted perpendicular anisotropy on SOT-induced magnetization switching and DW motion,and are beneficial for designs of further SOT-based devices.
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