講演情報
[21p-C501-15]Field-free spin-orbit torque magnetization switching in a perpendicularly magnetized (Ga,Mn)As single layer
〇(M2)Xinyuan Yang1, Chenda Wang1, Miao Jiang1,2, Shinbu Ohya1,3, Masaaki Tanaka1,3 (1.Univ. Tokyo, 2.Beijing Inst of Technology, 3.CSRN,Univ. Tokyo)
キーワード：
Spin-Orbit-Torque、Field free switching、Dzyaloshinskii Moriya (DM) interaction
Current-induced spin-orbit torque (SOT) magnetization switching has been actively studied because it is expected to be used for magnetoresistive random access memory (MRAM) and other spintronics devices. While conventional SOT devices generally consider a ferromagnet/spin source bilayer structure, we have recently realized highly efficient SOT magnetization switching in a perpendicularly magnetized ferromagnetic semiconductor (Ga,Mn)As single layer with a very low current density (< 105 A cm-2) 1,2. Usually, the SOT switching in the systems with perpendicular magnetic anisotropy (PMA) needs an external magnetic field to achieve deterministic magnetization switching. For better scalability and switching efficiency in spintronics devices, field-free SOT magnetization switching in a ferromagnet is required.
Here we report a field-free SOT switching in a (Ga,Mn)As single layer with PMA. Figure 1a will show the sample structure, composed of (Ga0.9,Mn0.1)As (7 nm) / In0.3Ga0.7As (500 nm) / GaAs (50 nm), grown by molecular beam epitaxy (MBE). After the MBE growth, the sample was annealed at 200 ℃ for 60 hours to improve the quality of (Ga,Mn)As. The Curie temperature TC was estimated to be 120 K. Figure 1b will show the crossbar structure (10μm10μm) for SOT measurements. As shown in Figs. 1c and 1d, when the current is applied along or [110], respectively, partial SOT switching occurs at T = 3.7 K or 50 K even without external magnetic field Hex. Figures 1e and 1f show microscopic simulation results, which can well explain the experimental results. In our simulation model, we introduced an effective magnetic field caused by the Dzyaloshinskii–Moriya (DM) interaction to break the symmetry, leading to the field-free deterministic magnetization switching.
Here we report a field-free SOT switching in a (Ga,Mn)As single layer with PMA. Figure 1a will show the sample structure, composed of (Ga0.9,Mn0.1)As (7 nm) / In0.3Ga0.7As (500 nm) / GaAs (50 nm), grown by molecular beam epitaxy (MBE). After the MBE growth, the sample was annealed at 200 ℃ for 60 hours to improve the quality of (Ga,Mn)As. The Curie temperature TC was estimated to be 120 K. Figure 1b will show the crossbar structure (10μm10μm) for SOT measurements. As shown in Figs. 1c and 1d, when the current is applied along or [110], respectively, partial SOT switching occurs at T = 3.7 K or 50 K even without external magnetic field Hex. Figures 1e and 1f show microscopic simulation results, which can well explain the experimental results. In our simulation model, we introduced an effective magnetic field caused by the Dzyaloshinskii–Moriya (DM) interaction to break the symmetry, leading to the field-free deterministic magnetization switching.