Integration of Tb/Co multilayers within optically switchable perpendicular magnetic tunnel junctions

Abstract

This work reports the development of perpendicular magnetic tunnel junctions, based on a multilayered stack of [Tb/Co] nanolayers, in which the magnetization can be reliably toggled using a single optical pulse. The helicity-independent single-shot switching of the magnetization in the Tb/Co multilayered stack was achieved using either 60 fs-long or 5 ps laser pulses with incident fluences down to 4.7 mJ/cm2. The magnetic switching was achieved for a Co-rich composition window of the multilayer corresponding to layer thickness ratios tCo/tTb between 1.3-1.5. This was confirmed for the multilayer alone as well as for the multilayer coupled to aCoFeB electrode, with a structure consisting of CoFeB/Ta/[Tb/Co]N. The optical switching is preserved even after annealing at 250°C in magnetic tunnel junctions (MTJ) electrodes, exhibiting a tunnel magnetoresistance (TMR) of 41% and RxA value of 150 Ωμm after its integration, measured on unpatterned MTJ stacks. These results represent the first step towards the development of hybrid spintronic photonic systems with fJ switching energies.