A Study Of Spin Transport And Interface Properties In Several Heusler Compounds

On a mesoscopic scale,the interface has a crucial impact on the performance of de-vices for the study of spintronics.As a device model for the study of the Giant magnetore-sistance（GMR）effect,the Spin-Valve（SV）is a sandwich multi-layer structure composed of non-magnetic metal spacer material separating by two magnetic electrodes.Therefore,two interfaces are formed between the electrode and the spacer material.Atomic disorder and defects at the interface will significantly destroy the GMR per-formance of the SV.In order to reduce the disorder at the interface and protect the half metallicity of the electrode at the same region,we propose a scheme to construct a spin valve by replacing the Y-site atoms in the half-metallic Heusler electrode to obtain the corresponding non-magnetic spacer based on the Slater-Pauling rule.In this way,the lat-tice and band match of the two materials can be ensured naturally.By using Co2Fe Al as an electrode and Co2Sc Al as the spacer materials,the Co2Fe Al/Co2Sc Al/Co2Fe Al（001）-SV is constructed.Based on the first-principles calculation,the most stable Fe Al/Co Co-interface is determined both from the phonon spectra and the formation energy when the spacer Co2Sc Al grows on the Fe Al-terminated（001）surface of electrode material Co2Fe Al.By comparing the projected density of states of the interfacial atoms with the corresponding density of states of the bulk electrode material,only the value of the spin-up state of Al changes from 0.17 states/atom/e V to 0.06 states/atom/e V before and after the substitution,the half metallicity at the interface is maintained.As a result,the spin-dependent transport properties show significant theoretical MRop which can reach up to10¹⁰%and is much larger than 10~6%reported before in“all-Heusler”device.As a com-parison,we further explored the MR properties of SVs composed of two groups of Heusler compounds Fe3Al/Fe2VAl and Mn3Al/Cu3Al respectively,and further verified the feasi-bility of our device scheme.Based on the concern of the interface properties of heterostructures in magnetoresis-tive devices,we constructed heterostructures with topological nontrivial and topological trivial materials to explore the possibility of interface magnetism.At the same time,in the wide-bandgap semiconductor,Li3Sb shows surface magnetism when Li（X-Site）is used as the surface at[001]and[111]crystal orientation,and this surface magnetism shows strong robustness to various external perturbations.