Epitaxial growth, structural characterization, and exchange bias of noncollinear antiferromagnetic Mn3Ir thin films

Antiferromagnetic materials are of great interest for spintronics. Here we present a comprehensive study of the growth, structural characterization, and resulting magnetic properties of thin films of the noncollinear antiferromagnet Mn3Ir. Using epitaxial engineering on MgO (001) and Al2O3 (0001) single-crystal substrates, we control the growth of cubic γ-Mn3Ir in both (001) and (111) crystal orientations, and discuss the optimization of growth conditions to achieve high-quality crystal structures with low surface roughness. Exchange bias is studied in bilayers, with exchange bias fields as large as -29 mT (equivalent to a unidirectional anisotropy constant of 0.115ergcm-2 or 11.5nJcm-2) measured in Mn3Ir (111)/Permalloy heterostructures at room temperature. In addition, a distinct dependence of blocking temperature on in-plane crystallographic direction in Mn3Ir (001)/Permalloy bilayers is observed. These findings are discussed in the context of antiferromagnetic domain structures, and will inform progress towards chiral antiferromagnetic spintronic devices.