Collaborative Work on Probing Momentum-Space Spin Polarization in Altermagnets via the Anomalous Hall Effect Published in Physical Review Letters
Our collaborative work with Professors Rui Chen and Bin Zhou’s team at Hubei University and Professors Rui Wang and Dong-Hui Xu’s team at Chongqing University has been published in Physical Review Letters 135, 096602 (2025). The study proposes a theoretical approach to probe the momentum-space spin polarization of altermagnets using topological surface states and the anomalous Hall effect.
A defining feature of altermagnets is their sign-alternating spin polarization in momentum space, yet direct electrical probes of this property remain limited. This collaborative study proposes coupling an altermagnet to the surface of a topological insulator, where the altermagnetic proximity effect induces a momentum-dependent, sign-alternating mass in the surface Dirac states. This gives rise to a characteristic alternating half-quantized anomalous Hall response.
By tuning an in-plane magnetic field, the surface Dirac point can be shifted through momentum space, allowing the magnitude and sign of the Hall conductance to probe the local magnetic information and map the momentum-space spin polarization. The approach is further shown to apply to altermagnetic orders with different symmetries and to remain robust against moderate disorder, providing a transport-based route for characterizing altermagnets and other unconventional antiferromagnets.