Effect of an antiferromagnetic layer on the temperature dependence of coercivity in biased FeMn/Co systems

The hysteresis loops of exchange-biased FeMn/Co bilayers have been measured by means of a superconducting quantum interference device magnetometer. Th e obtained right and left coercivities exhibit different temperature depend ences. With temperature increasing, the left coercivity monotonously increa ses while the right one remains almost constant until a critical temperatur e T-i. Upon decreasing the thickness of the antiferromagnet (AF) layer, T-i decreases. The asymmetric behavior of the right and left coercivities indi cates that the reversal mechanisms are different for increasing and decreas ing field. By taking into account the temperature dependence of the spin al ignment in the AF layer, the unusual asymmetric behavior is well explained. (C) 2001 American Institute of Physics.