Tailoring topological altermagnetic spin texture via interfacial exchange coupling in quasi-2D CrSb-(Bi, Sb)₂Te₃

The integration of magnetism and topologically nontrivial electronic states has opened exciting avenues for realizing novel quantum phases and functionalities in condensed matter systems. In the quasi-2D altermagnet/topological insulator heterostructures, interfacial effects (e.g., strain and exchange coupling) play a central role and offer unique opportunities to investigate emerging physical phenomena not present in quasi-3D or bulk systems. In this talk, we will report a pronounced anomalous Hall effect (AHE) and tunable spin anisotropy arising from symmetry-breaking of the altermagnetic order in CrSb (2.4 nm)/(Bi_1-xSb_x)₂Te₃ heterostructure. The AHE strength, driven by the modulation of altermagnetic spin texture orientation, can be tuned through strain via the film thickness and Fermi level control of the topological insulator (Bi_1-xSb_x)₂Te₃ by Sb concentration. The effective Hamiltonian model reveals that the exchange coupling between the altermagnetic order and topology can produce a unique hybrid AHE. Angle-dependent magneto-transport uncovers the magnetic dynamics of altermagnetic moments with exchange coupling. Our strategy broadens the way to explore altermagnetic interfacial physics and topological spintronics in quasi-2D altermagnet/topological insulators.