Ultrafast demagnetization enhancement in CoFeB/MgO/CoFeB magnetic tunneling junction driven by spin tunneling current

TLDR

The study aims to enable manipulation of ultrafast spin currents in magnetic tunneling junctions. The authors use time‑resolved magneto‑optical Kerr effect to probe laser‑induced ultrafast demagnetization in CoFeB/MgO/CoFeB junctions in both parallel and antiparallel magnetization states. They find that the antiparallel state exhibits faster and larger demagnetization due to ultrafast spin transfer through hot‑electron tunneling, demonstrating that hot‑electron currents can engineer ultrafast demagnetization.

Abstract

The laser-induced ultrafast demagnetization of CoFeB/MgO/CoFeB magnetic tunneling junction is exploited by time-resolved magneto-optical Kerr effect (TRMOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the AP state than those in the P state. These behaviors are attributed to the ultrafast spin transfer between two CoFeB layers via the tunneling of hot electrons through the MgO barrier. Our observation indicates that ultrafast demagnetization can be engineered by the hot electrons tunneling current. It opens the door to manipulate the ultrafast spin current in magnetic tunneling junctions.