Magnetic Phase Transition of La_1-xSr_xMnO₃ Induced by Charge Transfer and Interdiffusion

Rare earth manganites under hole doping, R_1-xB_xMnO₃ (R = La, Nd, Pr and B = Sr, Ca, Ba), have a rich charge carrier-temperature-magnetism phase diagram. The phases are tunable by applying external constraints, such as strain and boundary conditions. For example, the ferromagnetic phase dominated by the double-exchange mechanism can be transformed into an antiferromagnetic phase by controlling the doping level. In this work, using first principles calculations based on density functional theory, we study the bilayer system La_0.67Sr_0.33MnO₃ (LSMO)/SrRuO₃ (SRO) composed of two ferromagnetic materials. The original ferromagnetism in LSMO becomes A-type antiferromagnetism at the interface. Such intriguing behavior at transition-metal oxide interfaces in the LSMO/SRO bilayer, stemming from coexisting interdiffusion and charge transfer from the SRO layer, is similar to a hole-doped LSMO layer attached to a substrate with electric polarization. Our result qualitatively and quantitatively explains recent experimental evidence of a dramatic change in the strength of magnetization for different terminations of LSMO/SRO bilayers.