Electrical Manipulation of Noncollinear Antiferromagnetic State Via Orbital Hall Effect

Orbital Hall effect can induce spin-orbit torque in ferromagnetic heterostructures with similar symmetry as spin Hall effect. Due to its weak dependence on spin-orbit coupling, even light metals like Cr could exhibit robust orbital Hall conductivity and generate comparable spin-orbit torque as heavy metals. In view of this, we study the electrical control of antiferromagnetic state in Mn3Sn/Cr and ferromagnetic state in CoFeB/Cr. We find that Cr can induce efficient switching in both Mn3Sn and CoFeB despite its negligible spin Hall angle. However, from terahertz emission and magnetoresistance measurements, the inverse process - spin-to-charge conversion in Cr/CoFeB is much less efficient than the heavy metal-based structures. These results suggest that the observed switching in Mn3Sn/Cr and CoFeB/Cr is mainly contributed by orbital Hall effect rather than spin Hall effect.