Search

Quantum materials harbor a cornucopia of exotic transport phenomena challenging our understanding of condensed matter. Among these, a giant, nonsaturating linear magnetoresistance (MR) has been reported in various systems, from Weyl semimetals to topological insulators. Its origin is often ascribed to unusual band structure effects, but it may also be caused by extrinsic sample disorder. Here, we report a very large linear MR in a SrTiO3two-dimensional electron gas and, by combining transport measurements with electron spectromicroscopy, show that it is caused by nanoscale inhomogeneities that are self-organized during sample growth. Our data also reveal semiclassical Sondheimer oscillations arising from interferences between helicoidal electron trajectories, from which we determine the 2DEG thickness. Our results bring insight into the origin of linear MR in quantum materials, expand the range of functionalities of oxide 2DEGs, and suggest exciting routes to explore the interaction of linear MR with features like Rashba spin–orbit coupling.

The quantum coupling of fully different degrees of freedom is a challenging path towards new functionalities for quantum electronics. Here we show that the localized classical spin of a magnetic atom immersed in a superconductor with a two-dimensional electronic band structure gives rise to a long-range coherent magnetic quantum state. We experimentally evidence coherent bound states with spatially oscillating particle–hole asymmetry extending tens of nanometres from individual iron atoms embedded in a 2H–NbSe2crystal. We theoretically elucidate how reduced dimensionality enhances the spatial extent of these bound states and describe their energy and spatial structure. These spatially extended magnetic states could be used as building blocks for coupling coherently distant magnetic atoms in new topological superconducting phases.