Tuning Rashba type spin-orbit field via Mn composition gradient engineering in (Ga,Mn)As ferromagnetic films

초록

The study investigated how out-of-plane structural inversion asymmetry (SIA) influences current induced spin-orbit fields (SOFs) in crystalline (Ga,Mn)As ferromagnetic films. By growing (Ga,Mn)As films in which the manganese composition is gradually increased or decreased along the growth direction of the film, we systematically control the out-of-plane SIA in the films. Using Hall measurements designed to probe current-induced SOFs, we identify both Dresselhaus-type SOF, arising from bulk inversion asymmetry, and the Rashba-type SOF, originating from SIA of the films. While the sign of the Dresselhaus-type SOFs remains unchanged regardless of the out-of-plane asymmetry direction (i.e., ascending or descending order variation of Mn composition in the film), the Rashba-type SOFs exhibit opposite orientations depending on the Mn gradient along the growth direction. These results provide direct experimental evidence of out-of-plane SIA-driven Rashba-type SOF modulation and establish a robust platform for engineering spin-orbit torque phenomena in ferromagnetic semiconductor systems. © 2025 Elsevier B.V., All rights reserved.

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