用于自旋转移力矩的新型多功能Heusler化合物的设计方案

Tunnel magnetoresistance and spin-transfer-torque switching in polycrystalline Co2FeAl full-Heusler alloy magnetic tunnel junctions on Si/SiO2 amorphous substrates

We studied polycrystalline B2-type Co2FeAl (CFA) full-Heusler alloy based magnetic tunnel junctions (MTJs) fabricated on a Si/SiO2 amorphous substrate. Polycrystalline CFA films with a (001) orientation, a high B2 ordering, and a flat surface were achieved using a MgO buffer layer. A tunnel magnetoresistance (TMR) ratio up to 175% was obtained for an MTJ with a CFA/MgO/CoFe structure on a 7.5-nm-thick MgO buffer. Spin-transfer torque induced magnetization switching was achieved in the MTJs with a 2-nm-thick polycrystalline CFA film as a switching layer. Using a thermal activation model, the in…

Band structure and transport studies of half Heusler compound DyPdBi: An efficient thermoelectric material

The discovery of Heusler alloys has revolutionized the research field of intermetallics due to the ease with which one can derive potential candidates for multifunctional applications. During recent years, many half Heusler alloys have been investigated for their thermoelectric properties. The f electron based rare earth ternary half Heusler compound DyPdBi has its f energy levels located close to the Fermi energy level. Other research efforts have emphasized that such materials have good thermoelectric capabilities. We have explored using first principles the electronic band structure of DyPd…

作为压电体的半赫斯勒半导体

Half-Heusler semiconductors as piezoelectrics

材料科学的核心挑战之一是设计功能和多功能材料，其中施加的场和应力产生大的响应。这种材料的合理设计的一个快速发展的范例是基于一个大的材料家族的第一性原理研究，钙钛矿氧化物是典型的情况。具体而言，结构和性质的第一性原理计算被用来探索感兴趣的功能性质的微观起源，并搜索平衡和亚稳相的大空间，以确定有前途的候选系统。在本文中，我们使用第一性原理的合理设计方法来证明半导体半Heusler化合物作为一个以前未被认识的一类压电材料，并提供指导的实验实现和进一步研究的高性能材料适合于实际应用。

用于自旋电子学应用的新型Heusler材料：生长、表征与应用

Novel Heusler Materials for Spintronic Applications: Growth, Characterizations and Applications

本文综述了新型Heusler合金（如半金属铁磁体、自旋无隙半导体等）的合成、表征与输运性质，强调其可调谐特性对下一代自旋电子器件的关键作用。

Guidelines for understanding cubic manganese-rich Heusler compounds

Manganese-rich Heusler compounds are attracting much interest in the context of spin transfer torque and rare-earth free hard magnets. Here we give a comprehensive overview of the magnetic properties of non-centrosymmetric cubic Mn$_2$-based Heusler materials, which are characterized by an antiparallel coupling of magnetic moments on Mn atoms. Such a ferrimagnetic order leads to the emergence of new properties that are absent in ferromagnetic centrosymmetric Heusler structures. In terms of the band structure calculations, we explain the formation of this magnetic order and the Curie temperatur…

Half-Heusler topological insulators

Ternary semiconducting or metallic half-Heusler compounds with an atomic composition 1:1:1 are widely studied for their flexible electronic properties and functionalities. Recently, a new material property of half-Heusler compounds was predicted based on electronic structure calculations: the topological insulator. In topological insulators, the metallic surface states are protected from impurity backscattering due to spin-momentum locking. This opens up new perspectives in engineering multifunctional materials. In this article, we introduce half Heusler materials from the crystallographic and…

Magnetism in tetragonal manganese-rich Heusler compounds

A comprehensive study of the total energy of manganese-rich Heusler compounds using density functional theory is presented. Starting from a large set of cubic parent systems, the response to tetragonal distortions is studied in detail. We single out the systems that remain cubic from those that most likely become tetragonal. The driving force of the tetragonal distortion and its effect on the magnetic properties, especially where they deviate from the Slater--Pauling rule, as well as the trends in the Curie temperatures, are highlighted. By means of partial densities of states, the electronic …

自旋能隙金属：一类用于多功能自旋电子器件的新型材料

Spin gapped metals: A novel class of materials for multifunctional spintronic devices

受能隙金属启发，提出“自旋能隙金属”概念，其每个自旋通道独立表现出本征p/n型特征且无带尾缺陷；通过第一性原理计算在半Heusler化合物中验证其可行性，为下一代多功能器件铺路。

Giant anomalous Hall and Nernst effect in magnetic cubic Heusler compounds

The interplay of magnetism and topology opens up the possibility for exotic linear response effects, such as the anomalous Hall effect and the anomalous Nernst effect, which can be strongly enhanced by designing a strong Berry curvature in the electronic structure. It is even possible to utilize this to create a quantum anomalous Hall state at high temperatures by reducing the dimensionality. Magnetic Heusler compounds are a promising class of materials for this purpose because they grow in thin films, have a high Curie temperature, and their electronic structure hosts strong topological featu…

Spin Hall Conductivity and Anomalous Hall Conductivity in Full Heusler compounds

The spin Hall conductivity (SHC) and anomalous Hall conductivity (AHC) in more than 120 full Heusler compounds are calculated using density functional theory in a high-throughtput way. The electronic structures are mapped to the Wannier basis and the linear response theory is used to get the conductivity. Our results show that the mechanism under the SHC or AHC cannot be simply related to the valence electron numbers or atomic weights, is related to the very details of the electronic structure, which can only be obtained by calculations. A high throughput calculation is efficient to screen out…

降低CPP-GMR器件中自旋转移矩诱导磁化反转的临界电流：$Co_2FeGa_{0.5}Ge_{0.5}$ 赫斯勒合金的低阻尼与增强自旋散射不对称性效应

Reducing critical current for spin-transfer-torque-induced magnetization reversal in CPP-GMR devices: effect of low damping and enhanced spin scattering asymmetry in $Co_2FeGa_{0.5}Ge_{0.5}$ Heusler alloy

本研究利用$Co_2FeGa_{0.5}Ge_{0.5}$赫斯勒合金的低阻尼与高自旋极化特性，通过将其用作自由层及与CoFe构成双层自旋注入层，有效降低了CPP-GMR器件中STT诱导磁化反转的临界电流，提升了器件效率与稳定性。

Co基Heusler化合物中反常霍尔电流的高自旋极化

High spin polarization of the anomalous Hall current in Co-based Heusler compounds

基于本征反常和自旋霍尔电导的第一性原理密度泛函计算，我们预测了Co基全Heusler化合物Co $_2$ XZ中的电荷霍尔电流（X = Cr和Mn; Z = Al、Si、Ga、Ge、In和Sn），除了Co $_2$之外，即使Co $_2$ MnAl，Co $_2$ MnGa，Co $_2$ MnIn和Co $_2$ MnSn不具有半金属能带结构。此外，相关的自旋电流与电荷霍尔电流的比率略大于1.0。这表明这些Co基Heusler化合物，特别是Co $_2$ MnAl，Co $_2$ MnGa和Co $_2$ MnIn，它们被发现具有大的反常和自旋霍尔电导率，可以被称为反常霍尔半金属，并且可以在自旋电子学例如自旋阀以及磁阻和自旋扭矩驱动的纳米器件中具有有价值的应用。这些有趣的发现进行了讨论，在计算的电子能带结构，磁矩和异常和自旋霍尔电导率作为费米能级的函数。

Magnetoelastic and Magnetostrictive Properties of Co$_2$XAl Heusler Compounds

We present a comprehensive first principles electronic structure study of the magnetoelastic and magnetostrictive properties in the Co-based Co$_2$XAl (X = V, Ti, Cr, Mn, Fe) full Heusler compounds. In addition to the commonly used total energy approach, we employ torque method to calculate the magnetoelastic tensor elements. We show that the torque based methods are in general computationally more efficient, and allow to unveil the atomic- and orbital-contributions to the magnetoelastic constants in an exact manner, as opposed to the conventional approaches based on second order perturbation …

半金属Co$_2$MnSi Heusler薄膜中电流的自旋极化

Spin-polarization of the electric current in half-metallic Co$_2$MnSi Heusler thin films

利用自旋波多普勒频移测量，在MgO/Co$_2$MnSi/MgO薄膜中确定电流完全自旋极化，证实半金属能带结构转化为完全自旋极化电流，并估算了非绝热自旋转移力矩参数。

数据存储：Heusler化合物综述

Data Storage: Review of Heusler Compounds

近十年来，Heusler化合物家族在自旋电子学领域引起了巨大的科学和技术兴趣。这主要是由于其特殊的磁性，使其成为各种数据存储设备中有前途的功能材料，如巨磁阻自旋阀，磁性隧道结和自旋转移扭矩器件。在这篇文章中，我们提供了一个全面的审查Heusler家族在磁数据存储的应用。除了它们在这些设备的性能改进中的重要作用之外，我们还试图指出当前基于Heusler的设备的挑战以及可能的解决方案。我们希望这篇综述能激发进一步的研究工作，通过充分激发其内在潜力，将这一杰出的材料家族有效地纳入数据存储应用。

Growth, strain and spin orbit torques in epitaxial NiMnSb films sputtered on GaAs

We report current-induced spin torques in epitaxial NiMnSb films on a commercially available epi-ready GaAs substrate. The NiMnSb was grown by co-sputtering from three targets using optimised parameter. The films were processed into micro-scale bars to perform current-induced spin-torque measurements. Magnetic dynamics were excited by microwave currents and electric voltages along the bars were measured to analyse the symmetry of the current-induced torques. We found that the extracted symmetry of the spin torques matches those expected from spin-orbit interaction in a tetragonally distorted h…

Giant spin Hall effect in half-Heusler alloy topological semimetal YPtBi grown at low temperature

Half-Heusler alloy topological semimetal YPtBi is a promising candidate for an efficient spin source material having both large spin Hall angle $θ$$_{SH}$ and high thermal stability. However, high-quality YPtBi thin films with low bulk carrier density are usually grown at 600$°$C, which exceeds the limitation of 400$°$C for back end of line (BEOL) process. Here, we investigate the crystallinity and spin Hall effect of YPtBi thin films grown at lower growth temperature down to 300$°$C. Although $θ$$_{SH}$ degraded with lowering the growth temperature to 300$°$C due to degradation of the crystal…

Spin pumping and spin torque in interfacial tailored Co2FeAl/\b{eta}-Ta layers

The Heusler ferromagnetic (FM) compound Co2FeAl interfaced with a high-spin orbit coupling non-magnetic (NM) layer is a promising candidate for energy efficient spin logic circuits. The circuit potential depends on the strength of angular momentum transfer across the FM/NM interface; hence, requiring low spin memory loss and high spin-mixing conductance. To highlight this issue, spin pumping and spin-transfer torque ferromagnetic resonance measurements have been performed on Co_2FeAl/β-Ta heterostructures tailored with Cu interfacial layers. The interface tailored structure yields an enhanceme…

单层MnCoGa中体自旋轨道转矩的对称性依赖极性反转

Symmetry-Dependent Polarity Reversal of Bulk Spin-Orbit Torque in Single-Layer MnCoGa

研究在单层MnCoGa赫斯勒合金中实现体自旋轨道转矩，发现其极性反转源于晶格畸变诱导的对称性破缺而非自旋霍尔电导率符号变化，确立应变调控对称性为体SOT调控的新自由度。

单自旋轨道矩器件中的可重构自旋逻辑与高密度多态存储器

Reconfigurable Spin Logics and High-density Multistate Memory in a Single Spin-orbit Torque Device

本研究将自旋轨道矩与面外磁场结合，在单个W/Pt/Co/AlOx异质结SOT器件中实现可重构多态逻辑运算，并通过两步写入工艺达成SOT基器件最高多态存储密度，为高密度多功能存内逻辑器件提供新路径。

Unidirectional magnetoresistance and spin-orbit torque in NiMnSb

Spin-dependent transport phenomena due to relativistic spin-orbit coupling and broken space-inversion symmetry are often difficult to interpret microscopically, in particular when occurring at surfaces or interfaces. Here we present a theoretical and experimental study of spin-orbit torque and unidirectional magnetoresistance in a model room-temperature ferromagnet NiMnSb with inversion asymmetry in the bulk of this half-heusler crystal. Besides the angular dependence on magnetization, the competition of Rashba and Dresselhaus-like spin-orbit couplings results in the dependence of these effect…

磁性隧道结Mn $_{3-δ}$ Ga/MgO界面的研究

Investigation on Mn$_{3-δ}$Ga/MgO interface for magnetic tunneling junctions

Mn $_3$ Ga Heusler化合物及其合金是实现磁隧道结自旋转移矩开关最有前途的材料。通过这些多层结构化器件中的高质量界面可以实现改进的性能。在这种情况下，Mn $_{1.63}$ Ga和MgO之间的界面由于其在隧道结中的自旋极化性质而特别令人感兴趣。我们用硬X射线光电子能谱学（HAXPES）对MgO/Mn $_{1.63}$ Ga结进行了化学表征。实验表明，在界面处的Ga-O键的形成，并证明在MgO膜附近的Mn原子的局部环境的变化。此外，我们表明，插入的金属镁层界面的MgO和锰-镓膜强烈抑制镓的氧化。

Room-temperature spin-orbit torque in NiMnSb

Materials that crystalize in diamond-related lattices, with Si and GaAs as their prime examples, are at the foundation of modern electronics. Simultaneoulsy, the two atomic sites in the unit cell of these crystals form inversion partners which gives rise to relativistic non-equilibrium spin phenomena highly relevant for magnetic memories and other spintronic devices. When the inversion-partner sites are occupied by the same atomic species, electrical current can generate local spin polarization with the same magnitude and opposite sign on the two inversion-partner sites. In CuMnAs, which share…