Electronic reconstruction induced inverted hysteresis loop in La_0.67Sr_0.33MnO₃/Pb(Zr_0.52Ti_0.48)O₃ superlattices

The multiferroic heterointerfaces, based on perovskite transition metal oxides, have been established as the effective way to build an interface with emergent phenomena owing to the coexistence and competition of complex interaction at the interface. Here, the La_0.67Sr_0.33MnO₃/Pb(Zr_0.52Ti_0.48)O₃ (LSMO/PZT) multiferroic superlattices (SLs) grown on (001)-, (110)-, and (111)-oriented SrTiO₃ substrates have been systematically investigated. An inverted hysteresis loop (IHL) with a negative coercivity and remanence was found in the (001)- and (111)-oriented SLs, while was absent in (110)-oriented SLs. Detailed magnetic measurements demonstrate the contribution of both scanning field and temperature to the IHL, and the positive exchange bias in the minor hysteresis loops indicates the antiferromagnetic coupling between the interface and the bulk. The polarity discontinuity at the (001)- and (111)-oriented LSMO/PZT interface leads to the charge redistribution and is responsible for the unexpected IHL phenomenon. Our study highlights the significance of the electronic reconstruction due to the polarity discontinuity at the interface and provides a new approach to deal with complex magnetic interactions at the interface.