Spin Hall effect from hybridized 3d-4p orbitals

We show that a paramagnetic CoGa compound possesses large enough spin Hall angle to allow robust spin-orbit torque switching of perpendicularly magnetized ferrimagnetic MnGa films in CoGa/MnGa/oxide heterostructures. The spin Hall efficiency estimated via spin Hall magnetoresistance and harmonic Hall measurements is +0.05±0.01, which is surprisingly large for a system that does not contain any heavy metal element. First-principles calculations corroborate our experimental observations and suggest that the hybridized Co 3d-Ga 4p orbitals are responsible for the intrinsic spin Hall effect. Our results suggest that efficient spin current generation can be realized in intermetallics by alloying a transition metal with a p-orbital element and by Fermi-level tuning.