MRAM Device Incorporating Single-Layer Switching via Rashba-Induced Spin Torque

作者：Guo Jie^*; Tan Seng Ghee; Jalil Mansoor Bin Abdul; Eason Kwaku; Lua Sunny Yan Hwee; Rachid Sbiaa; Meng Hao

来源：IEEE Transactions on Magnetics, 2011, 47(10): 3868-3871.

DOI：10.1109/TMAG.2011.2158634

• Magnetic RAM (MRAM)
• Rashba spin-orbit interaction
• spin transfer torque (STT)

We designed and modeled a nonvolatile memory device that utilizes the Rashba spin-orbit coupling (SOC) to write data onto a free ferromagnetic (FM) layer and uses the tunneling magnetoresistive (TMR) effect for data read-back. The magnetic RAM (MRAM) device consists of a free (switchable) FM multilayer stack, in which a large internal electric field is induced at the interfaces between the oxide and the FM layer. In the FM layer, data writing by magnetization switching occurs via the Rashba-induced spin torque, while the data reading process in the system could be fulfilled via the current-perpendicular-to-plane TMR response. A general equation of motion for the local moments has been obtained by formally deriving the SU(2) spin-orbit gauge field arising due to SOC and the critical current density is estimated to be 1.2 x 10(8) A/cm(2). Micromagnetic simulations were performed to demonstrate the Rashba-induced switching mechanism. By choosing or fabricating alloys with a lower magnetocrystalline anisotropy and enhancing the Rashba coupling strength via surface or interfacial engineering, the critical current may be further reduced to well below 10(7) A/cm(2), a level that may enable the practical realization of a single-layer Rashba-induced magnetization switching memory.

• 出版日期2011-10