On December 9, 2024, Assistant Professor Wang Chen published a research paper in the Nature Index journal "Physical Review B" titled "Thermal switching across the ultrafast amorphous to crystalline transition in Sc0.2Sb2Te3." This study systematically reveals the intrinsic mechanisms between atomic motion, anharmonic lattice dynamics, and the abrupt change in thermal conductivity in Scandium Antimony Telluride alloy (Sc0.2Sb2Te3) during the ultrafast crystalline-amorphous transition process. Assistant Professor Wang Chen is the first author, Associate Professor Chen Yue from the Department of Mechanical Engineering at the University of Hong Kong is the corresponding author, and the Institute for Advanced Study of Shenzhen University is the leading institution for the publication.
The research team constructed an efficient machine learning potential of Sc0.2Sb2Te3, a leading candidate in phase change materials for exceptional subnanosecond memory writing, with moment tensor descriptors by fitting a large set of reference quantum-mechanical data to depict the complex potential energy surfaces in both amorphous and crystalline states of Sc0.2Sb2Te3. The large-scale molecular dynamics simulations confirm an octahedron-heptagon reconfiguration related to the Sc-centered atomic motifs with a slight distortion accompanying the phase transition, responsible for the exceptional recrystallization kinetics of Sc0.2Sb2Te3. Furthermore, the density fluctuations analysis based on hydrodynamic theory reveals a jump of thermal conductivity with the highest predicted switch ratio of 2.4 between amorphous and crystalline of Sc0.2Sb2Te3, which is further benchmarked by the heat-flux-independent nonequilibrium molecular dynamics simulations. Finally, the unified lattice dynamical approach（QHGK）rationalizes the thermal conductivity evolution by linking Te-dominated anharmonic lattice dynamics and thermal switching. This research provides new theoretical guidance for exploring the atomic dynamics behavior in rapid phase-change alloys and their applications in thermal switches.
This work is supported by the Research Grants Council of Hong Kong (C7002-22Y, 17318122, and C6020-22GF).
Link: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.110.214202
Fig. 1. Schematic diagram of the thermal switching mechanism in Scandium Antimony Telluride alloy system.
