In-plane spin-orbit torque magnetization switching and its detection using the spin rectification effect at subgigahertz frequencies

Abstract

In-plane magnetization reversal of a permalloy/platinum bilayer was detected using the spin rectification effect. Using a sub-GHz microwave frequency to excite spin-torque ferromagnetic resonance (ST-FMR) in the bilayer induces two discrete DC voltages around an external static magnetic field of 0 mT. These discrete voltages depend on the magnetization directions of the permalloy and enable detection of the in-plane magnetization reversal. The threshold current density for the magnetization reversal is around 10-20 MA/cm², the same order as for known spin-orbit torque (SOT) switching with in-plane magnetization materials. The magnitude of the signal is the same or larger than that of the typical ST-FMR signal; that is, detection of magnetization switching is highly sensitive in spite of deviation from the optimal ST-FMR condition. The proposed method is applicable to a simple device structure even for a small ferromagnetic electrode with a width of 100 nm.

Efficient room-temperature magnetization direction detection by means of the enhanced anomalous Nernst effect in a Weyl ferromagnet

“…On the other hand, over the past decade it has been proved that spin torques originated by the spin-orbit interaction (a relativistic effect in solids) allow the magnetization switching of a ferromagnetic layer, the main mechanisms to accomplish it being the Rashba interaction and the spin Hall effect (SHE), which are electric current driven and do not require a fixed reference ferromagnet (FM) [18][19][20]. Such systems provide a technique to write a ferromagnetic memory element, but the counterpart reading scheme, i.e., a method to detect 180 • magnetization reversal by purely electrical means in a practical scale, remains a challenge for physics [21].…”