Antiferromagnetic magnetostriction of IrMn detected by angular dependent exchange bias

Abstract

The manipulation of Néel vector of antiferromagnetic (AFM) layer by an applied stress has attracted considerable attention due to the technical importance for AFM-based spintronic devices. Here, we fabricated CoFeB/IrMn and Ni/IrMn exchange bias (EB) bilayers on PMN-PT(011) to quantitatively study the AFM magnetostrictive behaviors of the IrMn layer. Numerical calculations based on the Stoner–Wohlfarth model show that the response of the Néel vector to compressive stress can be detected by measuring the angular dependent EB. The hysteresis loops experimentally measured with applying an electric field on PMN-PT show significantly different shape changes due to the opposite magnetostriction between CoFeB and Ni. The non-vanished EB field obtained at 90∘ indicates the rotation of Néel vector under compressive stress, suggesting the positive magnetostriction of IrMn. The numerical fitting of the angular dependent EB indicates that the Néel vectors in both samples deviate from the initial direction by the same −5∘. The AFM magnetostriction coefficient of IrMn is estimated to be 238 ppm, which is in good agreement with the theoretically predicted value.