Persistence of spin memory in a crystalline, insulating phase-change material

The description of disorder-induced electron localization by Anderson over 60 years ago began a quest for novel phenomena emerging from electronic interactions in the presence of disorder. Even today, the interplay of interactions and disorder remains incompletely understood. This holds in particular for strongly disordered materials where charge transport depends on 'hopping' between localized sites. Here we report an unexpected spin sensitivity of the electrical conductivity at the transition from diffusive to hopping conduction in a material that combines strong spin-orbit coupling and weak inter-electronic interactions. In thin films of the disordered crystalline phase change material SnSb2Te4, a distinct change in electrical conductance with applied magnetic field is observed at low temperatures. This magnetoconductance changes sign and becomes anisotropic at the disorder-driven crossover from strongly localized (hopping) to weakly localized (diffusive) electron motion. The positive and isotropic magnetoconductance arises from disruption of spin correlations that inhibit hopping transport. This experimental observation of a recently hypothesized 'spin memory' demonstrates the spin plays a previously overlooked role in the disorder-driven transition between weak and strong localization in materials with strong spin-orbit interactions.