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

Abstract Altermagnets featuring collinear magnetic order and momentum-space spin splitting are a newly identified class of magnetically ordered materials. Most studies so far on altermagnetism focus on quasi-3D (e.g., > 10 nm) systems with bulk symmetry-dominance, while the quasi-2D regime with symmetry-breaking remains largely unexplored. Here, we report a pronounced anomalous Hall effect and tunable spin anisotropy arising from symmetry-breaking of the altermagnetic order in CrSb (2.4 nm)/(Bi 1- x Sb x ) 2 Te 3 heterostructures. The anomalous Hall effect strength, driven by the modulation of altermagnetic spin texture orientation, can be tuned through strain via controlling the thickness and Fermi level of the topological insulator (Bi 1- x Sb x ) 2 Te 3 . The effective Hamiltonian model reveals that the exchange coupling between the altermagnetic order and topology can produce a unique hybrid anomalous Hall effect. Angle-dependent magneto-transport investigation 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 insulator heterostructures.