Modulation of the 2DEGs mediated by 3<i>d</i>-4<i>f</i> exchange interaction via the stacking sequences

Spin-polarized two-dimensional electron gases (2DEGs) at complex oxide heterointerfaces exhibit intriguing properties and provide great opportunities for spintronics devices. In this work, we investigate the modulation of 2DEGs' properties at the interfaces between LaTiO3 and EuTiO3 films by altering the stacking sequences of the heterostructures. We demonstrate that different stacking sequences lead to distinct mechanisms for compensating the polar discontinuity at the interfaces, which significantly influence the coupling between itinerant electrons and local moments. As a result, an asymmetric metallic and magnetic behavior of 2DEGs at LaTiO3/EuTiO3 vs EuTiO3/LaTiO3 interfaces is observed. These findings establish a method for controlling the exchange interaction between the conducting 3d electrons of 2DEGs and the 4f localized moments of Eu2+ ions. This approach not only deepens our understanding of the physics of complex oxide heterostructures but also opens up an avenue for manipulating spin-polarized 2DEGs, with potential implications for the design of next-generation oxide-based spintronic devices.