Extreme magnetoresistance in γ-Al₂O₃/SrTiO₃

Magnetic field-induced changes in the electrical resistance can provide a large amount of information on the electronic and magnetic structure of a studied material. A specific type of magnetoresistance, extreme magnetoresistance (XMR), is often associated with a non-saturating magnetoresistance in materials with a gapless band structure such as topological and non-topological materials.

For this work, a linear, non-saturating magnetoresistance (MR) of 80,000% at 15 T and 2 K at the high-mobility interface between the insulating γ-Al₂O₃ and SrTiO₃ is presented. Temperature/field phase diagrams of the data revealed three crossover magnetic fields that are strongly reminiscent of the temperature/field response of semimetals displaying XMR.

Further analysis of the magnetotransport data, probing of the band structure and microscopic current imaging suggests that weak disorder provokes a squeezed guiding center motion of electrons, which induces an XMR response. Due to the dynamic origin of the high-mobility interface, the linear XMR can be tuned via redistribution of oxygen vacancies, making it an excellent candidate material for magnetic field sensing applications.

This research presents a mechanistic origin of XMR in the γ-Al₂O₃/SrTiO₃ heterostructure and provides with an experimental pathway for employing this highly correlated heterostructure into the next generation of magnetic field sensors, using a geometric enhancement of the magnetoresistance.