近日，美国加州大学圣巴巴拉分校A. F.Young课题组与康奈尔大学Jie Shan及科罗拉多大学丹佛分校的M.E.Huber等人合作，研究了莫尔陈（moiré Chern）磁铁中的固有自旋霍尔扭矩。相关成果已于2023年3月9日在国际学术期刊《自然—物理学》上发表。
该研究团队在单个二维系统中证实了具有内禀磁性和强Berry曲率的自旋-轨道扭矩磁比特。他们研究了AB -堆叠的MoTe2/WSe2，其在每个moiré超晶格位置携带一个空穴密度时具有磁性陈氏绝缘体特性。他们观察到电阻率随外加电流呈现出滞后切换的特性，而磁成像揭示电流切换对应于单个磁畴的反转。这些磁畴的真实空间模式与具有高Berry曲率的哈伯德带边缘附近测量的自旋累积相一致。这表明，本征自旋或谷霍尔扭矩驱动了在MoTe2/WSe2和其他莫尔材料中观察到的电流激励磁性切换。值得一提的是，切换电流密度大大低于其他平台报道的，这表明莫尔异质结构是一个有效控制磁序的合适平台。
据介绍，在自旋扭矩磁存储器中，利用电激励自旋电流来切换磁比特。通常，这些存储器需要一个多层几何结构，包括一个自由铁磁层和提供自旋注入的第二层。例如，可以通过表现出大自旋霍尔效应的非磁性层来注入自旋，这种现象称为自旋-轨道扭矩。
附：英文原文
Title: Intrinsic spin Hall torque in a moiré Chern magnet
Author: Tschirhart, C. L., Redekop, Evgeny, Li, Lizhong, Li, Tingxin, Jiang, Shengwei, Arp, T., Sheekey, O., Taniguchi, Takashi, Watanabe, Kenji, Huber, M. E., Mak, Kin Fai, Shan, Jie, Young, A. F.
Issue&Volume: 2023-03-09
Abstract: In spin torque magnetic memories, electrically actuated spin currents are used to switch a magnetic bit. Typically, these require a multilayer geometry including both a free ferromagnetic layer and a second layer providing spin injection. For example, spin may be injected by a non-magnetic layer exhibiting a large spin Hall effect, a phenomenon known as spin–orbit torque. Here we demonstrate a spin–orbit torque magnetic bit in a single two-dimensional system with intrinsic magnetism and strong Berry curvature. We study AB-stacked MoTe2/WSe2, which hosts a magnetic Chern insulator at a carrier density of one hole per moiré superlattice site. We observe hysteretic switching of the resistivity as a function of applied current. Magnetic imaging reveals that current switches correspond to reversals of individual magnetic domains. The real space pattern of domain reversals aligns with spin accumulation measured near the Hubbard band edges with high Berry curvature. This suggests that intrinsic spin or valley Hall torques drive the observed current-driven magnetic switching in both MoTe2/WSe2 and other moiré materials. The switching current density is substantially less than those reported in other platforms, suggesting that moiré heterostructures are a suitable platform for efficient control of magnetic order.
DOI: 10.1038/s41567-023-01979-8
Source: https://www.nature.com/articles/s41567-023-01979-8