Positive exchange bias and inverted hysteresis loop in Y 3 Fe 5 O 12 / Gd 3 Ga 5 O 12

We present evidence of an unprecedented room temperature positive exchange bias (EB) and hysteresis loop inversion in monolithic Y3Fe5O12 films grown epitaxially on a (111)-oriented Gd3Fe5O12 crystal. The growth-induced interfacial Gd3Fe5O12 layer couples antiparallel to the Y3Fe5O12 layer and leads to positive EB and in-turn loop inversion. An exchange shift as large as H-EB similar to H-30(c) is realized at 300 K. We observe a critical field value of H-CF similar to 600 Oe, above which the hysteresis loop inversion takes place. Our findings may have strong implication for spintronics device applications.