Spin-orbit fields induced by topological insulator in (Ga,Mn)As/Bi2Te3 heterostructures

초록

We investigate current-induced spin-orbit fields (SOFs) in a bilayer heterostructure composed of a ferromagnetic semiconductor (Ga,Mn)As and a topological insulator (Bi2Te3). Planar Hall resistance (PHR) measurements at 3 K during field rotation reveal clear current polarity-dependent hysteresis shifts when the magnetization transitions involve a change perpendicular to the current direction, whereas no shifts are observed when the magnetization change is collinear to the current. This behavior confirms the presence of effective SOFs oriented perpendicular to the current direction. The magnitude of the hysteresis shift decreases with increasing external magnetic field, enabling quantitative extraction of SOF components using a magnetic free energy model. By analyzing PHR data for currents along [110] and [11<overline>0], we separately determine the Dresselhaus- and the net Rashba-type SOFs, with the latter including contributions from both (Ga,Mn)As and the Bi2Te3 surface states. The net Rashba-type SOF is found to be negative, demonstrating that the SOF contribution from the Bi2Te3 surface states opposes and outweighs that of intrinsic Rashba-type SOF in (Ga,Mn)As. These findings provide direct evidence that topological surface states significantly tune current-induced SOFs in FMS/TI bilayers, offering a promising route toward efficient, all-electrical spintronic devices.

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