Persistence of spin memory in the insulating state of the crystalline phase-change material SnSb₂Te₄ revealed by magnetotransport measurements

Understanding the driving mechanisms for quantum materials, whether strongly correlated, strongly disordered, or characterized by nontrivial band topology, often derives from precise studies of electronic lifetimes. Sufficiently long electronic spin and phase-coherence lifetimes result in weak localization or (in the presence of strong spin-orbit coupling) antilocalization, effects that can be used to spectroscopically probe complex materials. Here we identify a distinct, complementary phenomenon that can also be used to probe electronic lifetimes in strongly disordered materials [1]. We find an unexpected spin sensitive hopping conductivity in the phase change material SnSb₂Te₄ that can be tuned with disorder. An isotropic magnetoconductance arises from disruption of spin correlations that inhibit hopping transport, the recently described ‘spin memory’ effect [2], whose occurrence signals that the spin plays a previously overlooked role in the disorder-driven transition between weak and strong localization in spin-orbital materials. [1] J. Reindl, H. Volker, N. Breznay, M. Wuttig, npj Qauntum Materials (2019). [2] O. Agam, I. Aleinder, B. Spivak PRB 89, 100201(R) (2014).