2次元アルターマグネットの証拠を明らかにする新しいトポロジカル顕微鏡探針（New Topological Microscope Tip Reveals Evidence of 2D Altermagnetism）

2026-10-13 中国科学院（CAS）

＜関連情報＞

• https://english.cas.cn/newsroom/research-news/202610/t20261012_1202297.shtml
• https://www.nature.com/articles/s41586-026-11257-1

らせんトンネル効果による2次元d波オルタ磁性体の原子スケールスピンセンシング Atomic-scale spin sensing of a 2D d-wave altermagnet via helical tunneling

Zhuying Wang, Shuikang Yu, Xingkai Cheng, Xiaoyu Xiao, Wanru Ma, Yitian Ma, Feixiong Quan, Hongxi Song, Kunming Zhang, Yunmei Zhang, Wenhao Liu, Priti Yadav, Haohao Sheng, Aifeng Wang, Xiangbiao Shi, Zhijun Wang, Qian Niu, Yang Gao, Bin Xiang, Junwei Liu, Zhenyu Wang & Xianhui Chen
Nature  Published: 13 October 2026
DOI:https://doi.org/10.1038/s41586-026-11257-1  Early provide

Abstract

Altermagnets simultaneously possess momentum-dependent nonrelativistic spin splitting and zero net magnetization (1-6). Their defining crystalline symmetry connects opposite-spin sublattices in real space and imposes alternating spin polarization on the symmetry-related electronic states in momentum space (1-3). Identifying such an order and its associated spin response therefore calls for atomic-scale spin-sensitive measurements in both real and momentum space, an experimental milestone yet to be achieved. Here we show that the helical edge modes of the higher-order topological insulator α-Bi₄Br₄ can serve as a spin-selective scanning tunnelling microscopy probe of the two-dimensional d-wave altermagnetic order in the surface layer of KV₂Se₂O. Atomically registered mapping reveals the spatial relationship between the two V sublattices and a density-wave lattice modulation, as well as real-space patterns consistent with the checkerboard antiferromagnetic order. Field-dependent spectroscopy further finds opposite energy shifts of the unidirectional quasiparticle excitations extending along two orthogonal crystal axes and a predominantly out-of-plane magnetic response. In momentum space, spin-sensitive quasiparticle interference imaging reveals a bias-reversing d-wave anisotropy between the symmetry-paired X and Y valleys. These results provide converging evidence for two-dimensional d-wave altermagnetism on the surface of KV₂Se₂O and demonstrate helical-edge-mode tunnelling as a route for atomic-scale spin sensing in quantum materials.