Extraordinary temperature dependent magnetic anisotropy of the non-collinear antiferromagnet IrMn

Abstract

The magnetic anisotropy of antiferromagnets plays a crucial role in stabilising the magnetisation of many spintronic devices. In non-collinear antiferromagnets such as IrMn the symmetry and temperature dependence of the effective anisotropy are poorly understood. Theoretical and experimental calculations of the effective anisotropy constant for IrMn differ by two orders of magnitude, while the symmetry has been calculated as uniaxial in contradiction to the assumed relationship between crystallographic symmetry and temperature dependence of the anisotropy from the Callen-Callen law. In this letter we determine the effective anisotropy energy surface of \Lonetwo - \IrMn using an atomistic spin model and constrained Monte Carlo simulations. We find that meta-stable spin structures lower the overall energy barrier to a tenth of that estimated from simple geometrical considerations, significantly reducing the discrepancy between experiment and theory. The temperature scaling of the anisotropy energy barrier shows an exponent of \factor, close to a uniaxial exponent of 3. Our results demonstrate the importance of non-collinear spin states on the thermal stability of antiferromagnets with consequences for the practical application of antiferromagnets in devices operating at elevated temperatures.

arXiv comment5 pages, 4 figures

References in corpus (8)

• Antiferromagnetic spintronics
• Electrical switching of an antiferromagnet
• Atomistic spin model simulations of magnetic nanomaterials
• Constrained Monte Carlo Method and Calculation of the Temperature Dependence of Magnetic Anisotropy
• Electrical switching of antiferromagnetic Mn${}_2$Au and the role of thermal activation
• Giant magnetic anisotropy of the bulk antiferromagnets IrMn and IrMn3
• Atomistic spin-model based on a new spin-cluster expansion technique: Application to the IrMn3/Co interface
• The Landau-Lifshitz equation in atomistic models

Cited by in corpus (11)

• Observation of current-induced switching in non-collinear antiferromagnetic IrMn${}_3$ by differential voltage measurements
• Temperature scaling of two-ion anisotropy in pure and mixed anisotropy systems
• The origin of exchange bias in multigranular non-collinear IrMn${}_3$/CoFe thin films
• The atomistic origin of the athermal training effect in granular IrMn/CoFe bilayers
• Domain periodicity in an easy-plane antiferromagnet with Dzyaloshinskii-Moriya interaction
• Experimental Observation of a Magnetic Interfacial Effect
• Spin wave excitations in exchange biased IrMn/CoFe bilayers
• Understanding Field-Free Single-Shot Laser-Induced Reversal of Exchange Bias
• Local setting of spin textures in a granular antiferromagnet
• Orthogonal Spin-Orbit Torque-Induced Deterministic Switching in NiO
• Understanding the non-collinear antiferromagnetic IrMn${}_3$ surfaces and their exchange-biased heterostructures from first principles