近日，英国诺丁汉大学的P. Wadley及其研究团队取得一项新进展。他们实现了碲化锰中纳米级电磁成像与控制。相关研究成果已于2024年12月11日在国际权威学术期刊《自然》上发表。

据悉，纳米尺度上磁序的检测与控制，是涉及磁性的凝聚态研究和器件功能化的基础。其关键原理在于打破时间反演对称性，这一特性在铁磁体中由内部磁化产生。然而，净磁化的存在限制了器件的可扩展性，以及与超导体、拓扑绝缘体等相位的兼容性。近期，反铁磁体作为解决这些限制的一种方案被提出，因为它兼具铁磁体打破时间反演对称性的特性，同时其净磁化类似反铁磁体而消失。迄今为止，反铁磁序是通过空间平均探测来推断的。

本文展示了碲化锰（MnTe）中反铁磁态的纳米尺度成像，涵盖了从100纳米尺度的涡旋和畴壁到10微米尺度的单畴状态。研究人员将X射线磁圆二色性的时间反演对称性破缺敏感性，与磁线二色性和光发射电子显微镜相结合，实现了对局部反铁磁序矢量的映射。

通过使用微结构图案化和磁场中的热循环，研究人员实现了多种自旋配置的施加。对反铁磁自旋配置的检测和控制形成，为未来在理论上预测的反铁磁研究领域进行实验研究铺平了道路，这些研究包括非传统自旋极化现象、反铁磁与超导和拓扑相位的相互作用，以及高度可扩展的数字和神经形态自旋电子器件。

附：英文原文

Title: Nanoscale imaging and control of altermagnetism in MnTe

Author: Amin, O. J., Dal Din, A., Golias, E., Niu, Y., Zakharov, A., Fromage, S. C., Fields, C. J. B., Heywood, S. L., Cousins, R. B., Maccherozzi, F., Krempask, J., Dil, J. H., Kriegner, D., Kiraly, B., Campion, R. P., Rushforth, A. W., Edmonds, K. W., Dhesi, S. S., mejkal, L., Jungwirth, T., Wadley, P.

Issue&Volume: 2024-12-11

Abstract: Nanoscale detection and control of the magnetic order underpins a spectrum of condensed-matter research and device functionalities involving magnetism. The key principle involved is the breaking of time-reversal symmetry, which in ferromagnets is generated by an internal magnetization. However, the presence of a net magnetization limits device scalability and compatibility with phases, such as superconductors and topological insulators. Recently, altermagnetism has been proposed as a solution to these restrictions, as it shares the enabling time-reversal-symmetry-breaking characteristic of ferromagnetism, combined with the antiferromagnetic-like vanishing net magnetization. So far, altermagnetic ordering has been inferred from spatially averaged probes. Here we demonstrate nanoscale imaging of altermagnetic states from 100-nanometre-scale vortices and domain walls to 10-micrometre-scale single-domain states in manganese telluride (MnTe). We combine the time-reversal-symmetry-breaking sensitivity of X-ray magnetic circular dichroism with magnetic linear dichroism and photoemission electron microscopy to achieve maps of the local altermagnetic ordering vector. A variety of spin configurations are imposed using microstructure patterning and thermal cycling in magnetic fields. The demonstrated detection and controlled formation of altermagnetic spin configurations paves the way for future experimental studies across the theoretically predicted research landscape of altermagnetism, including unconventional spin-polarization phenomena, the interplay of altermagnetism with superconducting and topological phases, and highly scalable digital and neuromorphic spintronic devices.

DOI: 10.1038/s41586-024-08234-x

Source: https://www.nature.com/articles/s41586-024-08234-x