Spin-generation in magnetic Weyl semimetal Co₂MnGa across varying degree of chemical order

Abstract

<jats:p> Recently discovered magnetic Weyl semimetals (MWSM), with enhanced Berry curvature stemming from the topology of their electronic band structure, have gained much interest for spintronics applications. In this category, Co<jats:sub>2</jats:sub>MnGa, a room temperature ferromagnetic Heusler alloy, has garnered special interest as a promising material for topologically driven spintronic applications. However, until now, the structural-order dependence of spin current generation efficiency through the spin Hall effect has not been fully explored in this material. In this paper, we study the evolution of magnetic and transport properties of Co<jats:sub>2</jats:sub>MnGa thin films from the chemically disordered B2 to ordered L2<jats:sub>1</jats:sub> phase. We also report on the change in spin generation efficiency across these different phases, using heterostructures of Co<jats:sub>2</jats:sub>MnGa and ferrimagnet Co<jats:sub> x</jats:sub>Tb<jats:sub>1−</jats:sub><jats:sub> x</jats:sub> with perpendicular magnetic anisotropy. We measured large spin Hall angles in both the B2 and L2<jats:sub>1</jats:sub> phases, and within our experimental limits, we did not observe the advantage brought by the MWSM ordering in generating a strong spin Hall angle over the disordered phases, which suggests more complicated mechanisms over the intrinsic, Weyl-band structure-determined spin Hall effect in these material stacks. </jats:p>