Current-induced switching in a magnetic insulator

Abstract

Electrical currents at the surface or edge of a topological insulator are intrinsically spin-polarized. We show that such surface/edge currents can be used to switch the orientation of a molecular magnet weakly coupled to the surface or edge of a topological insulator. For the edge of a two-dimensional topological insulator as well as for the surface of a three-dimensional topological insulator the application of a well-chosen surface/edge current can lead to a complete polarization of the molecule if the molecule's magnetic anisotropy axis is appropriately aligned with the current direction. For a generic orientation of the molecule a nonzero but incomplete polarization is obtained. We calculate the probability distribution of the magnetic states and the switching rates as a function of the applied current.

High-quality single-crystal thulium iron garnet films with perpendicular magnetic anisotropy by off-axis sputtering

“…The optimized films had the room-temperature saturation magnetization (M s ) of 99 emu/cm 3 (RT bulk value: 110 emu/cm 3 ) with an H c of 2.4 Oe, which was the lowest value ever reported for TmIG films. [7][8][9][10]12 TmIG films with low coercive field require low current induced effective field to switch the magnetization so that the current density of magnetization switching can be reduced. Fig.…”

“…Moreover, a current-induced magnetization switching has been demonstrated in Pt/TmIG heterostructure. 10 The spin Hall effect (SHE) induced spin currents injected to TmIG, exerting a torque and reversed the magnetization at low current densities, viable for ultralow-dissipation spintronic devices utilizing the FIs. The effective field H eff z to switch the magnetization is proportional to the applied current density J e and the SOT efficiency χ is defined as χ = H eff z J e .…”

“…These can be applied to data storage, magnetic random access memory, logic/memory utilizing domain wall. 10 Most reported TmIG films have been grown by pulsed laser deposition (PLD), [7][8][9][10]12 which is known to deposit thin films in a limited small area. Using magnetron sputtering to grow TmIG thin films is preferred because sputtering has been widely used in larger scale applications.…”

Spin transport in as-grown and annealed thulium iron garnet/platinum bilayers with perpendicular magnetic anisotropy

“…14 A second widely-studied effect is spin-orbit torque (SOT). [15][16][17][18][19] SOTs are current-induced torques exerted on the magnetization as a result of strong spin-orbit coupling and inversion asymmetry. These SOTs typically originate from the SHE in the bulk of the NM ( Fig.1 middle panels) and Rashba-Edelstein effect at the interfaces of dissimilar materials.…”

“…However, recently, SMR and strong SOTs have been reported in a thulium iron garnet (TmIG)/Pt bilayer system possessing perpendicular magnetic anisotropy (PMA). 15,30 The PMA in this system was exploited to demonstrate current-induced magnetization switching and direct electrical measurement of the damping-like SOT based on harmonic analysis of the SMR-driven Hall effect signal, 15,30 similar to all-metallic NM/ferromagnetic systems. Finally, the third prominent spin-dependent phenomenon is the spin Seebeck effect (SSE).…”