Anomalous magnetotransport at a two-dimensional correlated electron system

The emergent two-dimensional electron system (2DES) formed at the interface between LaAlO₃ (LAO) and SrTiO₃ (STO) insulating oxides has been a subject of great interest in condensed matter physics over the last decade. Recently, the (111)-oriented STO based 2DES has attracted further attention due to its sixfold orbital and lattice symmetry whereby two consecutive planes form a dense honeycomb lattice of Ti 3d orbitals, a host candidate for prospective topologically non-trivial electronic phases. Furthermore, we have demonstrated that the (111)-LAO/STO interface exhibits an electronic correlation driven reconstruction of its band structure, and a two-dimensional superconducting groundstate, both tunable by electrostatic field-effect.

In this work, we report on the magnetotronsport properties of the 2DES in both in-plane and out-of-plane magnetic field. In the planar Hall effect configuration we observe strongly gate-dependent large non-saturating magnetoresistive signal, with further plateau structures, when the sourced current is parallel to the applied external magnetic field. We tentatively relate the observed anomalous electronic transport to the complex band structure of the (111)-LAO/STO 2DES, exhibiting a number of avoided d_xz-d_yz-d_xy band crossings, sources of Berry phase.