Positive Exchange Bias between Permalloy and Twined (10-10)-Cr2O3 Films
  We report the discovery of a positive exchange bias between Ni80Fe20 (Py) and twined (10-10)-Cr2O3 film near its blocking temperature (TB) when it is cooled in an in-plane magnetic field applied along 45 degrees from the two spin configurations of the Cr atoms. This is an abnormal behavior compared to the negative exchange bias at all temperatures below TB when the cooling and measuring magnetic fields are applied along one of the two spin configurations of the Cr atoms. We speculate these results could be related to the exchange interactions between the twined structure of the (10-10)-Cr2O3 film epitaxially grown on the rutile (001)-TiO2 substrate. 
Wei Yuan, Tianyu Wang, Tang Su, Qi Song, Wenyu Xing, Yangyang Chen,   and Wei Han
cond-mat.mtrl-sci