From weak antilocalization to Kondo scattering in a magnetic complex oxide interface

Quantum corrections to electrical resistance can serve as sensitive probes of the magnetic landscape of a material. For example, interference between time-reversed electron paths gives rise to weak localization effects, which can provide information about the coupling between spins and orbital motion, while the Kondo effect is sensitive to the presence of spin impurities. Here, we use low-temperature magnetotransport measurements to reveal a gradual transition from weak antilocalization (WAL) to Kondo scattering in the quasi-two-dimensional electron gas formed at the interface between $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}₃$ and the Mott insulator $\mathrm{Nd}\mathrm{Ti}{\mathrm{O}}₃$. This transition occurs as the thickness of the $\mathrm{Nd}\mathrm{Ti}{\mathrm{O}}₃$ layer is increased. Analysis of the Kondo scattering and WAL points to the presence of atomic-scale magnetic impurities coexisting with nanoscale magnetic regions that affect transport via a strong magnetic exchange interaction. This leads to distinct magnetoresistance behaviors that can serve as a sensitive probe of magnetic properties in two dimensions.