Equilibrium surface magnetization of alpha-Cr2O3 studied through interfacial chromium magnetization in Co/alpha-Cr2O3 layered structures

We show experimental evidence of the equilibrium surface magnetization of alpha-Cr2O3(0001) by studying chromium magnetization at the Co(111)/alpha-Cr2O3(0001) interface. The soft X-ray magnetic circular dichroism intensity from uncompensated Cr spins was found to be almost independent of the interface roughness and exchange anisotropy energy. Moreover, no exchange bias training effect was found, except in the transition temperature regime, suggesting that the antiferromagnetic spin structure, including the interface spin arrangement, is in equilibrium. Furthermore, the exchange bias polarity was switched by magnetoelectric field cooling, which is also a salient feature of the surface magnetization of alpha-Cr2O3(0001). (C) 2014 The Japan Society of Applied Physics