Spin torque switching in triple-quantum dot device with ferromagnetic contacts for memory applications

We investigate the applicability of a triple quantum dot (TQD) device for memory operation, in which information is coded by the magnetization of a ferromagnetic (FM) electrode. In the presence of Rashba spin-orbit coupling, a high spin polarization of current can be generated in the TQD device to induce spin transfer switching of the FM electrode. We evaluate the spin current and spin torque via the Keldysh nonequilibrium Green’s function method. The calculated spin torque can be reversed symmetrically by applying an opposite bias voltage, thus enabling current-induced magnetization switching to be applied for data writing. Additionally, the charge current shows a large modulation when the magnetization of the FM electrode is switched, a feature which can be utilized for reading data. The ability to write and read data demonstrates the applicability of the TQD device for spin transfer torque-based memory.