Bimodal distribution of blocking temperature in exchange-biased ferromagnetic/antiferromagnetic bilayers

The blocking temperature (T-B) distribution of various polycrystalline ferromagnetic (F)/antiferromagnetic (AF) bilayers exhibits two distinct peaks. This is ascribed to the existence of two families of magnetic entities determining the temperature dependence of exchange bias. One is formed by the AF grains which undergo thermally activated magnetic reversal. The other is formed by F/AF disordered interfacial spins which exhibit spin-glass-like behavior. The bulk versus interfacial nature of these two families is indicated by the dependence of the TB distribution on the AF thickness.