Sign reversals of magnetization and exchange bias field induced by Lu3+ doping in La0.3-xLuxPr0.7CrO3

Abstract

We have investigated the phenomenon of negative magnetization and exchange bias effect in polycrystalline La_0.3-xLu_xPr_0.7CrO₃ (0 ≤ x ≤ 0.3). La_0.3Pr_0.7CrO₃ exhibits negative magnetization and positive exchange bias field below compensation temperature under an applied field of 1 kOe in field cooling mode due to the antiferromagnetic coupling between Pr³⁺ moment and canted Cr³⁺ moment with Cr³⁺ moment parallel to the direction of applied magnetic field. However, the phenomenon of negative magnetization disappears accompanied by a sign reversal of exchange bias field from positive to negative at low temperature for x ≥ 0.2 samples, which can be ascribed to the dominant role of G_zF_x order induced by Lu³⁺ doping and consequent spin rotation of Pr³⁺-Cr³⁺ coupling. Though the negative magnetization can still be observed for the x = 0.1 sample, negative exchange bias field occurs as the growth of G_zF_x ordering domain during the initial magnetization process, evidenced by the disappearance of negative magnetization and spin rotation of Pr³⁺-Cr³⁺ coupling after high magnetic field pulse.