Tunnelling magnetoresistance of the half-metallic compensated ferrimagnet Mn₂Ru_xGa

Tunnel magnetoresistance ratios of up to 40% are measured between 10 K and 300 K when the highly spin-polarized compensated ferrimagnet, Mn₂Ru_xGa, is integrated into MgO-based perpendicular magnetic tunnel junctions. Temperature and bias dependences of the tunnel magnetoresistance effect, with a sign change near −0.2 V, reflect the structure of the Mn₂Ru_xGa interface density of states. Despite magnetic moment vanishing at a compensation temperature of 200 K for $x≈0.8$⁠, the tunnel magnetoresistance ratio remains non-zero throughout the compensation region, demonstrating that the spin-transport is governed by one of the Mn sub-lattices only. Broad temperature range magnetic field immunity of at least 0.5 T is demonstrated in the same sample. The high spin polarization and perpendicular magnetic anisotropy make Mn₂Ru_xGa suitable for applications in both non-volatile magnetic random access memory cells and terahertz spin-transfer oscillators.