Presentation Information
[2P12]STM study of surface evolution and phase stability in Sn/Pt(111) systems
*Shi Qing1, Naoya Miura1, Fumio Komori2,3,4, Masaki Mizuguchi1,4,5,6, Toshio Miyamachi1,4 (1. Graduate School of Engineering and School of Engineering, Nagoya University, 2. Institute of Industrial Science, The University of Tokyo, 3. Department of Materials Science and Engineering, Institute of Science Tokyo, 4. Institute of Materials and Systems for Sustainability, Nagoya University, 5. Cutting-edge, International Research Units, Nagoya University Institute for Advanced Study, Nagoya University, 6. Center for Spintronics Research Network, Osaka University)
The bulk-truncated fcc (111)-surface of Pt3Sn has attracted attention for spintronic and energy-harvesting devices owing to the coexistence of bulk and topological states. While sputtered Pt3Sn films show type-II Dirac fermions, their polycrystallinity complicates surface studies. A bottom-up route—depositing Sn on Pt(111) and annealing—yields atomically flat, single-crystalline Pt3Sn(111) surfaces. Although Sn growth on Pt(111) has been studied, the lattice stability of Pt-Sn alloy layers versus Sn coverage and annealing remains unclear. Using STM, we show stabilization of Pt3Sn requires sufficient Sn within one-unit-cell layers. Annealing drives island coarsening, rounding, and disorder, while equilibrium shape analysis indicates nearly isotropic step energies. We also identify a new (3 × 3) superlattice near Pt3Sn step edges, stabilized by local strain relaxation.