Single-layer magnetic memory based on Rashba three-terminal quantum dot device

Abstract

It has been shown that three-terminal quantum dot (TTQD) devices and their variants can generate a rather high spin current in the presence of Rashba spin-orbit coupling (RSOC) at low temperature. The effect of contacting ferromagnetic (FM) electrodes to the TTQD devices is studied theoretically via the Keldysh non-equilibrium Green's function method. The spin torque and spin current in the system are subsequently calculated. It is found that the spin torque in the middle FM lead can be reversed symmetrically by applying a bias voltage with opposite sign. This suggests that current-induced magnetization switching can be applied for data writing. Moreover, the charge current shows significant modulation when the orientation of the FM moment is varied, a feature which can be utilized for reading data. Based on this, we propose an integrated Magnetic Random Access Memory (MRAM) device made up of Rashba TTQD unit cells. In each cell, the electron transport can be modulated by means of a gate voltage without the need for a transistor- unlike the case of conventional MRAMs. What is more, owing to the combination of RSOC and exchange interaction with the local FM moments, both the writing and reading process can be effected with a single FM layer. © 2011 American Institute of Physics.