Tailoring the degree of disorder in chalcogenide phase‐change materials (PCMs) plays an essential role in nonvolatile memory devices and neuro‐inspired computing. Upon rapid crystallization from the amorphous phase, the flagship Ge–Sb–Te PCMs form metastable rocksalt‐like structures with an unconventionally high concentration of vacancies, which results in disordered crystals exhibiting Anderson‐insulating transport behavior. Here, ab initio simulations and transport experiments are combined to extend these concepts to the parent compound of Ge–Sb–Te alloys, viz., binary Sb2Te3, in the metastable rocksalt‐type modification. Then a systematic computational screening over a wide range of homologous, binary and ternary chalcogenides, elucidating the critical factors that affect the stability of the rocksalt structure is carried out. The findings vastly expand the family of disorder‐controlled main‐group chalcogenides toward many more compositions with a tunable bandgap size for demanding phase‐change applications, as well as a varying strength of spin–orbit interaction for the exploration of potential topological Anderson insulators.

Disorder plays an essential role in shaping the transport properties of GeSbTe phase-change materials (PCMs) to enable nonvolatile memory technology. Recently, increasing efforts have been undertaken to investigate disorder in the stable hexagonal phase of GeSbTe compounds, focusing on a special type of swapping bilayer defects. This configuration has been claimed to be the key element for a new mechanism for phase-change memory. Here, we report a direct atomic-scale chemical identification of these swapping bilayer defects in hexagonal GeSb 2 Te 4 together with nanoscale atomic modeling and simulations. We identify the intermixing of Sb and Te in the bilayer to be the essential ingredient for the stability of the defects, and elucidate their abundance as due to the small energy cost. The bilayer defects are demonstrated to be ineffective in altering the electron localization nature that is relevant to transport properties of hexagonal GeSb 2 Te 4 . Our work paves the way for future studies of layer-switching dynamics in GeSbTe at the atomic and electronic level, which could be important to understand the new switching mechanism relevant to interfacial phase-change memory.

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 SnSb 2 Te 4 , 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.npj Quantum Materials (2019) 4:57 ; https://doi.

Wiley-VCH GmbH (Pb) were employed with a wave-function cutoff of 30 Ry leading to energy convergence below 2 meV per atom in the elemental phases. For disordered systems, a 2 × 2 × 2 k-point mesh shifted away from the Γ point was used to obtain energy convergence below 1 mRy per atom and to avoid the sampling of extrema of spurious defect-level bands. For the ordered systems, a shifted 2 × 2 × 1 k-point mesh was used.Research data are not shared.