Voltage-Driven Magnetization Switching via Dirac Magnetic Anisotropy and Spin-Orbit Torque in Topological-Insulator-Based Magnetic Heterostructures
Abstract
Electric field control of magnetization dynamics is fundamentally and technologically important for future spintronic devices. Here, based on electric field control of both magnetic anisotropy and spin-orbit torque, two distinct methods are presented for switching the magnetization in topological-insulator- (TI) magnetic-TI hybrid systems. The magnetic anisotropy energy in magnetic TIs is formulated analytically as a function of the Fermi level, and it is confirmed that the out-of-plane magnetization is always favored for the partially occupied surface band. Also proposed is a transistorlike device with the functionality of a nonvolatile magnetic memory that uses voltage-driven writing and the (quantum) anomalous Hall effect for readout. For magnetization reversal, by using parameters of Cr -doped (Bi1 -xSbx)2Te3 , we find the estimated source-drain current density and gate voltage are on the order of 104-105A/cm 2 and 0.1 V, respectively, below 20 K and the writing requires no external magnetic field. Also discussed is the possibility of magnetization switching by the proposed method in TI-ferromagnetic-insulator bilayers with the magnetic proximity effect.
- Publication:
-
Physical Review Applied
- Pub Date:
- September 2020
- DOI:
- 10.1103/PhysRevApplied.14.034031
- arXiv:
- arXiv:2009.06187
- Bibcode:
- 2020PhRvP..14c4031C
- Keywords:
-
- Condensed Matter - Materials Science;
- Condensed Matter - Mesoscale and Nanoscale Physics;
- Physics - Applied Physics
- E-Print:
- 12 pages, 8 figures