Giant tunnel magnetoresistance in Co2MnSi/Al-O/Co2MnSi magnetic tunnel junctions

In this study, we attempt to fabricate a MTJ using Co₂MnSi as both upper and lower electrodes. The (100)-oriented epitaxial Co₂MnSi bottom electrode was grown on Cr-buffered MgO(100) substrate at ambient temperature using inductively coupled plasma (ICP)-assisted magnetron sputtering. The film was subsequently annealed at 450degC in order to reduce site-disorder. The MTJ with a stacking structure of MgO(100)-subs./epitaxial Cr 40 nm/epitaxial Co₂MnSi 30 nm/Al-0 1.3 nm/ Co₂MnSi 10 nm/Ir22Mn78 10 nm/Ta 3 nm were deposited without breaking vacuum. The upper Co₂MnSi electrode was deposited at ambient temperature followed by annealing at 400degC before depositing Ir₂₂Mn₇₈ anti-ferromagnetic layer.