Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 14: Superconductivity: Properties and Electronic Structure
TT 14.10: Talk
Monday, March 9, 2026, 17:30–17:45, HSZ/0103
Layer-selective Cooper pairing in an alternately stacked transition metal dichalcogenide — Haojie Guo1, •Sandra Sajan1, Irián Sánchez-Ramírez1, Tarushi Agarwal2, Alejandro Blanco Peces1, Chandan Patra2, Maia G. Vergniory1, Rafael M. Fernandes3, Ravi Prakash Singh2, Fernando de Juan1, Maria N. Gastiasoro1, and Miguel M. Ugeda1 — 1Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain — 2Department of Physics, Indian Institute of Science Education and Research Bhopal, 462066 Bhopal, India — 3Department of Physics, The Grainger College of Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
Multigap superconductivity occurs when different superconducting gaps form on separate Fermi surfaces. In the layered material 4Hb-TaSSe, made of alternating trigonal (H) and octahedral (T) polymorph layers, we demonstrate the presence of two weakly coupled and spatially separated superconducting condensates. Using quasiparticle tunneling and Andreev reflection spectroscopy on each polymorph layer, we identify two gaps that differ in magnitude and internal structure. Their responses to temperature and magnetic field also differ: each gap opens at a distinct temperature and shows opposite resilience to magnetic fields, enabling selective external tuning of each condensate. A theoretical model supported by ab-initio calculations reproduces these features and accounts for the unusually high critical field in the T-layer, highlighting TMD polymorphs as tunable multigap superconductors.
Keywords: Transitional metal dichalcogenides; Correlated materials; Superconductivity; Charge density wave; Multigap superconductors