Magnetic and electrical transport signatures of uncompensated moments in epitaxial thin films of the non-collinear antiferromagnet Mn${}_3$Ir

Abstract

Non-collinear antiferromagnets, with either an L1${}_2$ cubic crystal lattice (e.g. Mn${}_3$Ir and Mn${}_3$Pt) or a D0${}_{19}$ hexagonal structure (e.g. Mn${}_3$Sn and Mn${}_3$Ge), exhibit a number of novel phenomena of interest to topological spintronics. Amongst the cubic systems, for example, tetragonally distorted Mn${}_3$Pt exhibits an intrinsic anomalous Hall effect (AHE). However, Mn${}_3$Pt only enters a non-collinear magnetic phase close to the stoichiometric composition and at suitably large thicknesses. Therefore, we turn our attention to Mn${}_3$Ir, the material of choice for use in exchange bias heterostructures. In this paper, we investigate the magnetic and electrical transport properties of epitaxially grown, face-centered-cubic $\gamma$-Mn${}_3$Ir thin films with (111) crystal orientation. Relaxed films of 10 nm thickness exhibit an ordinary Hall effect, with a hole-type carrier concentration of (2.24 $\pm$ 0.08) $\times$ 10${}^{23}$ cm${}^{-3}$. On the other hand, TEM characterization demonstrates that ultrathin 3 nm films grow with significant in-plane tensile strain. This may explain a small remanent moment, observed at low temperatures, shown by XMCD spectroscopy to arise from uncompensated Mn spins. Of the order 0.02 ${\mu }_B$ / atom, this dominates electrical transport behavior, leading to a small AHE and negative magnetoresistance. These results are discussed in terms of crystal microstructure and chiral domain behavior, with spatially resolved XML(C)D-PEEM supporting the conclusion that small antiferromagnetic domains, < 20 nm in size, of differing chirality account for the absence of observed Berry curvature driven magnetotransport effects.

References in corpus (17)

• Antiferromagnetic spintronics
• Interface-Induced Phenomena in Magnetism
• Large anomalous Hall effect driven by non-vanishing Berry curvature in non-collinear antiferromagnetic Mn3Ge
• Anomalous Hall effect arising from noncollinear antiferromagnetism
• Large magneto-optical Kerr effect and imaging of magnetic octupole domains in an antiferromagnetic metal
• Non-collinear Antiferromagnets and the Anomalous Hall Effect
• Strong, anisotropic anomalous Hall effect and spin Hall effect in chiral antiferromagnetic compounds Mn${}_{3}X$ ($X$ = Ge, Sn, Ga, Ir, Rh and Pt)
• Enhanced spin pumping efficiency in antiferromagnetic IrMn thin films around the magnetic phase transition
• Current-polarity dependent manipulation of antiferromagnetic domains
• Giant magnetic anisotropy of the bulk antiferromagnets IrMn and IrMn3
• Direct imaging of antiferromagnetic domains in Mn${}_2$Au manipulated by high magnetic fields
• Storing magnetic information in IrMn/MgO/Ta tunnel junctions via field-cooling
• Current induced torques in structures with ultra-thin IrMn antiferromagnet
• Loss of anisotropy in strained ultrathin epitaxial L10 Mn-Ga films
• Gradual pressure-induced change in the magnetic structure of the non-collinear antiferromagnet Mn${}_3$Ge
• Isothermal anisotropic magnetoresistance in antiferromagnetic metallic IrMn
• Epitaxial growth, structural characterization and exchange bias of non-collinear antiferromagnetic Mn${}_3$Ir thin films

Cited by in corpus (4)

• Anomalous and topological Hall effects in epitaxial thin films of the noncollinear antiferromagnet Mn${}_3$Sn
• Spin-Torque-driven Terahertz Auto Oscillations in Non-Collinear Coplanar Antiferromagnets
• Epitaxial growth and orientation-dependent anomalous Hall effect of noncollinear antiferromagnetic Mn${}_3$Ni${}_{0.35}$Cu${}_{0.65}$N films
• Nonequilibrium control of kagome metals