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 $\mathrm{M}{\mathrm{n}}_{3}\mathrm{Ir}$. Using epitaxial engineering on MgO (001) and $\mathrm{A}{\mathrm{l}}_{2}{\mathrm{O}}_{3}$ (0001) single-crystal substrates, we control the growth of cubic \ensuremath{\gamma}-$\mathrm{M}{\mathrm{n}}_{3}\mathrm{Ir}$ 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 \ensuremath{-}29 mT (equivalent to a unidirectional anisotropy constant of $0.115\phantom{\rule{0.16em}{0ex}}\mathrm{erg}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$ or $11.5\phantom{\rule{0.16em}{0ex}}\mathrm{nJ}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$) measured in $\mathrm{M}{\mathrm{n}}_{3}\mathrm{Ir}$ (111)/Permalloy heterostructures at room temperature. In addition, a distinct dependence of blocking temperature on in-plane crystallographic direction in $\mathrm{M}{\mathrm{n}}_{3}\mathrm{Ir}$ (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.