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We propose a numerical method, where first-principles calculations are combined with modified Monte Carlo simulations, and study the Néel temperature of antiferromagnetic IrMn and exchange bias effect in antiferromagnet/ferromagnet IrMn/CoFeB bilayers manipulated by the applications of tensile and compressive strains. The results show that both tensile and compressive strains linearly change the magnetic moment of Mn and the magnetocrystalline anisotropy of IrMn, and meanwhile, the uniaxially easy-axis directions under tensile and compressive strains are perpendicular. The strain-triggered increase in antiferromagnetic exchange coupling between Mn–Mn pairs is revealed and induces an up to 1.5 times enhancement of the Néel temperature of IrMn. Furthermore, the spontaneous and conventional exchange bias effects can be both observed under large tensile strains, also sensitive to the cooling field, and strongly enhanced roughly by 800% under 8 T in the application of 1.5% strain, which can be interpreted by the strain-induced high magnetocrystalline anisotropies. Thus, the tensile strains are better for controlling and optimizing the Néel temperature of IrMn and further exchange bias properties in IrMn-based heterostructures. This work establishes the correlations between microscopically and macroscopically magnetic responses to strain, indicating that strain can be an intriguing means of extrinsic manipulation of exchange bias, which is of importance for spintronic device applications. [ABSTRACT FROM AUTHOR]

Bilayers of an amorphous CoFeB ferromagnet coupled to an epitaxially grown IrMn antiferromagnet, whose anisotropy is fourfold symmetric, are modeled to study the angular (φ) dependence of magnetization reversal mechanism and exchange bias behavior, based on a modified Monte Carlo method. It is found that positive and negative exchange-bias field (HE) maximum values appear in the antiferromagnetic easy-axis directions, and the HE zero-value transition/return points exist in the antiferromagnetic hard-axis directions. Furthermore, the value of HE(φ) is well fitted by considering cos3φ/sin3φ terms with larger or comparable coefficients as compared to the first-order terms in the Fourier expansion. Finally, the microscopic spin configuration results evidence these phenomena originating from the tailoring of antiferromagnetic spins by simply rotating the field-cooling direction between antiferromagnetic easy- and hard-axis directions. We open an exchange-bias mode governed by antiferromagnetic fourfold anisotropy and propose a method to precisely detect antiferromagnetic higher-order anisotropies on an exchange-bias support. [ABSTRACT FROM AUTHOR]