Tailoring-compensated ferrimagnetic state and anomalous Hall effect in quaternary Mn–Ru–V–Ga Heusler compounds

Abstract

Abstract Cubic Mn2Ru x Ga Heusler compound is a typical example of compensated ferrimagnet with attractive potential for high-density, ultrafast, and low-power spintronic applications. In the form of epitaxial thin films, Mn2Ru x Ga exhibits high spin polarization and high tunability of compensation temperature by freely changing the Ru content x in a broad range (0.3 < x < 1.0). Herein Mn–Ru–Ga-based polycrystalline bulk buttons prepared by arc melting are systematically studied and it is found that in equilibrium bulk form, the cubic structure is unstable when x < 0.75. To overcome this limitation, Mn–Ru–Ga is alloyed with a fourth element V. By adjusting the content of V in the Mn2Ru0.75V y Ga and Mn2.25–y Ru0.75V y Ga quaternary systems, the magnetic compensation temperature is tuned. Compensation is achieved near 300 K which is confirmed by both the magnetic measurement and anomalous Hall effect measurement. The analyses of the anomalous Hall effect scaling in quaternary Mn–Ru–V–Ga alloy reveal the dominant role of skew scattering, notably that contributed caused by the thermally excited phonons, in contrast to the dominant intrinsic mechanism found in many other 3d ferromagnets and Heusler compounds. It is further shown that the Ga antisites and V content can simultaneously control the residual resistivity ratio (RRR) as well as the relative contribution of phonon and defect to the anomalous Hall effect a″/a′ in Mn–Ru–V–Ga, resulting in a scaling relation a″/a′ ∝ RRR1.8.