A simulation study of voltage-assisted low-energy switching of a perpendicular anisotropy ferromagnet on a topological insulator

作者：Ghosh Bahniman; Dey Rik; Register Leonard F; Banerjee Sanjay K

来源：Journal of Computational Electronics, 2017, 16(1): 120-126.

DOI：10.1007/s10825-016-0951-x

• Topological insulator (TI)
• Exchange interaction
• Spin transfer torque (STT)
• Voltage-controlled magnetic anisotropy (VCMA)
• Micromagnetic simulation

We present a novel memory device that consists of a thin ferromagnetic layer of Fe deposited on topological insulator thin film, Bi2Se3. The ferromagnetic layer has perpendicular anisotropy, due to MgO deposited on its top surface. When current is passed on the surface of Bi2Se3, the surface of the Bi2Se3 becomes spin polarized and strong exchange interaction occurs between the d electrons in the ferromagnet and the electrons conducting the current on the surface of the Bi2Se3. Part of the current is also shunted through the ferromagnet, which generates spin transfer torque in the ferromagnet. The exchange interaction torque along with voltage-controlled magnetic anisotropy allows ultralow-energy switching of the ferromagnet. We perform micromagnetic simulations and predict switching time of the order of 2.5 ns and switching energy of the order of 0.88fJ for a ferromagnetic bit with thermal stability of 43 k(B)T. Such ultralow-energy and high-speed switching of a perpendicular anisotropy ferromagnet on a topological insulator could be utilized for energy-efficient memory design.

• 出版日期2017-3