Theoretical Calculation Of Spin Hall Effect In Novel Two-dimensional Janus Materials

Spintronics utilizes the spin of electrons as an information carrier to achieve functions such as data storage,logical operation,and quantum computing.Spintronic devices have the advantages of low power consumption,high speed and high integration,and are considered as new devices that may overcome the physical limit of Moore’s Law,with broad application prospects.The quantum effects resulting from the spin of electrons are the basis of numerous intriguing phenomena in condensed matter and materials physics.The discovery of novel spin effects through new materials and the utilization and amplification of these effects in spin devices have become the forefront of current research in spintronics.Most spin effects necessitate an external magnetic field or magnetic atoms to produce them.However,Since the discovery of spin Hall effect,it can control spin in non-magnetic systems,realize spin injection and spin detection functions,which provides a very large space for the material selection of novel spin devices.At present,many spin devices based on spin Hall effect have been proposed and applied,such as spin field effect tubes,photosensitive spin devices,polarized light detectors,etc.The generation,manipulation and detection of spin Hall effect is becoming an important framework for the construction of spintronics.Therefore,the electronic properties and spin Hall effect of Cu-graphane and a new class of five-layer two-dimensional materials MAB₂D family are systematically studied based on first-principles calculations.The main research contents are as follows:1.We investigated the electronic properties and spin polarization transport properties of Cu-graphane,a new two-dimensional Janus material.Theoretical calculations indicate that this structure is thermodynamically and dynamically stable.The electronic band structure displays highly anisotropic Dirac fermions and appears as a shape similar to a node ring on the Fermi level.With the inclusion of spin-orbit coupling,we observed a large spin Hall conductivity near the Fermi level.By calculating the spin Berry curvature,we explain the reason why the spin Hall conductivity varies with the Fermi energy and show that there may be a large and easy to adjust spin Hall conductivity in Dirac system.This suggests a way to find high-performance spintronics materials.2.We studied the electronic properties and spin polarization transport properties of a novel class of five-atom layer two-dimensional Janus materials.By combining high-throughput with first-principles calculations,we systematically screen out a large number of stable structures and classify them by electronic band structure.We found the coexistence of the valley effect and the Rashba effect in some structures.While spin splitting contributes to the spin Hall effect,the physical mechanism is not identical.This prompted us to further investigate,and through the calculation and analysis of spin Berry curvature,we discovered that the Zeeman spin splitting and the Rashba spin splitting have opposite contribution mechanisms to spin Hall conductivity,and we explained this.Finally,we also study the effect of strain on the electronic structure and the intrinsic spin hall conductivity of the five-atom layer material,so as to realize the regulation behavior of spin Hall conductivity.Our research provides a new class of candidate materials for spin Hall transistor devices.