近日，德国慕尼黑工业大学的L. Chen及其研究团队取得一项新进展。经过不懈努力，他们通过角动量流动控制磁性特征。相关研究成果已于2024年9月4日在国际权威学术期刊《自然》上发表。

本研究表明，在Pt/Al/Fe/GaAs(001)多层结构中，当Fe膜足够薄时，在Pt层中施加面内电荷电流会导致铁磁共振场随微波频率的变化而发生偏移。这一实验观察结果被解释为电荷电流诱导的Fe磁晶各向异性ΔH_A的改变。研究人员发现，（1）ΔH_A随Fe膜厚度的增加而减小，并与阻尼类扭矩相关；（2）ΔH_A不仅取决于电荷电流的极性，还取决于磁化方向，即磁化方向反转时，ΔH_A的符号相反。这种改变的对称性符合电流诱导的自旋和/或轨道累积效应，它们分别作用于磁化的自旋和/或轨道分量。

在本研究中，由于Pt被视为典型的自旋电流源，因此自旋电流可能起主导作用。自旋电流对磁性的控制源于多数和少数自旋带的交换分裂的改变，这种改变提供了以往未知的功能，并可能在先进的自旋电子器件中发挥重要作用。

据悉，探索通过电学手段操控磁性材料有序参数的新策略，不仅对于深化人们对基础磁性的理解至关重要，而且对于发掘潜在应用同样具有重要意义。一个已成熟的概念是利用栅极电压，通过调节电容器结构中的载流子数量来控制磁性特性。

附：英文原文

Title: Signatures of magnetism control by flow of angular momentum

Author: Chen, L., Sun, Y., Mankovsky, S., Meier, T. N. G., Kronseder, M., Sun, C., Orekhov, A., Ebert, H., Weiss, D., Back, C. H.

Issue&Volume: 2024-09-04

Abstract: Exploring new strategies to manipulate the order parameter of magnetic materials by electrical means is of great importance not only for advancing our understanding of fundamental magnetism but also for unlocking potential applications. A well-established concept uses gate voltages to control magnetic properties by modulating the carrier population in a capacitor structure. Here we show that, in Pt/Al/Fe/GaAs(001) multilayers, the application of an in-plane charge current in Pt leads to a shift in the ferromagnetic resonance field depending on the microwave frequency when the Fe film is sufficiently thin. The experimental observation is interpreted as a current-induced modification of the magnetocrystalline anisotropy ΔH_A of Fe. We show that (1) ΔH_A decreases with increasing Fe film thickness and is connected to the damping-like torque; and (2) ΔH_A depends not only on the polarity of charge current but also on the magnetization direction, that is, ΔH_A has an opposite sign when the magnetization direction is reversed. The symmetry of the modification is consistent with a current-induced spin and/or orbit accumulation, which, respectively, act on the spin and/or orbit component of the magnetization. In this study, as Pt is regarded as a typical spin current source, the spin current can play a dominant part. The control of magnetism by a spin current results from the modified exchange splitting of the majority and minority spin bands, providing functionality that was previously unknown and could be useful in advanced spintronic devices.

DOI: 10.1038/s41586-024-07914-y

Source: https://www.nature.com/articles/s41586-024-07914-y