Optical Switching in Tb/Co-Multilayer Based Nanoscale Magnetic Tunnel Junctions

TL;DR

This paper demonstrates ultrafast optical switching of nanoscale magnetic tunnel junctions using femtosecond laser pulses, enabling high-speed, low-power magnetic memory with size-dependent switching behavior.

Contribution

It introduces a novel method for optical switching of Tb/Co multilayer-based MTJs at nanoscale, combining optical writing with electrical read-out, and explores size-dependent effects.

Findings

Single-shot switching demonstrated down to 20 nm cell size

Switching probability depends on cell size and magnetic parameters

Successful control of resistance states via laser fluence and magnetic field

Abstract

Magnetic tunnel junctions (MTJs) are elementary units of magnetic memory devices. For high-speed and low-power data storage and processing applications, fast reversal by an ultrashort laser pulse is extremely important. We demonstrate optical switching of Tb/Comultilayer-based nanoscale MTJs by combining optical writing and electrical read-out methods. A 90 fs-long laser pulse switches the magnetization of the storage layer (SL). The change in magnetoresistance between the SL and a reference layer (RL) is probed electrically across the tunnel barrier. Single-shot switching is demonstrated by varying the cell diameter from 300 nm to 20 nm. The anisotropy, magnetostatic coupling, and switching probability exhibit cell-size dependence. By suitable association of laser fluence and magnetic field, successive commutation between high-resistance and low-resistance states is achieved. The switching dynamics in a continuous film is probed with the magneto-optical Kerr effect technique. Our experimental findings provide strong support for the growing interest in ultrafast spintronic devices.