The Influence of temperature and applied magnetic field on the exchange bias effect of La1.5Ca0.5CoIrO6

Abstract

La1.5Ca0.5CoIrO6 is a re-entrant spin-glass double-perovskite that exhibits a non-negligible spontaneous exchange bias effect at low temperatures. When performing magnetization as a function of applied field [M(H)] measurements after cooling the sample in the presence of a magnetic field, the exchange bias is greatly enhanced. In this work we report a detailed investigation of the influence of the maximum applied field (Hm) on the exchange bias effect for M (H) curves measured with and without the presence of an applied field on cooling. In both cases the shift in the hysteresis loops decreases for increasing Hm. We have also investigated the influence of the cooling field on the exchange bias effect. By increasing the applied field on cooling there is an initial increase of the exchange bias, followed by a decrease of the effect for larger cooling fields. A detailed study of the magnetic evolution of the system with temperature showed that despite the enhancement of the coercive field observed at temperatures above the freezing of the spin-glass phase, there is no trace of exchange bias effect at these temperatures. We discuss our results in terms of the pinning of the spins at the magnetic interfaces.