Tunnel Magnetoresistance of an As-deposited Co2FeAl0.5Si0.5-based Magnetic Tunnel Junction on a Ta/Ru Buffer Layer

Abstract

A magnetic tunnel junction (MTJ) with a Co2FeAl0.5Si0.5 (CFAS) heusler film on a conductive Ta/Ru buffer layer was fabricated for the first time. In the as-deposited state, a highly B2-ordered CFAS film was obtained by using the Ta/Ru buffer layer. The Ta (110) buffer layer causes a Ru (002) buffer layer, which leads to the growth of CFAS with a B2 structure and a completely flat CFAS film. After 600 degrees C annealing, strain relaxation occurred in the Ta/Ru interface, and the surface roughness decreased; however, the B2-ordered CFAS film remained. Also, in the as-deposited state, a exchange-biased CFAS/AlOx/CFAS MTJ deposited on a Ta/Ru buffer layer exhibited a relatively high tunnel magnetoresistance (TMR) of 13% at room temperature, which resulted from the highly B2-ordered CFAS layer and the perfectly flat surface roughness resulting from the use of the Ta/Ru buffer layer.