Bosonic topological insulator intermediate state in the superconductor-insulator transition

• Published in: Physics letters. A Vol. 384; no. 23; p. 126570
• Main Authors: Diamantini, M.C., Mironov, A.Yu, Postolova, S.M., Liu, X., Hao, Z., Silevitch, D.M., Kopelevich, Ya, Kim, P., Trugenberger, C.A., Vinokur, V.M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 17.08.2020; Elsevier
• Subjects: Berezinskii-Kosterlitz-Thouless transition; Bose metal; Bosonic topological insulator; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Josephson junction arrays; Quantum Berezinskii-Kosterlitz-Thouless transition; Superconductor-insulator transition; Quantum Berezinskii-Kosterlitz-Thouless transition; Superconductor-insulator transition; Josephson junction arrays; Bose metal; Bosonic topological insulator; Berezinskii-Kosterlitz-Thouless transition
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2020.126570

•The intervening Bose metal (BM) state is the bosonic topological insulator.•In the bulk vortices and Cooper pairs are frozen by Aharonov-Bohm interactions.•Transport in the Bose metal is mediated by topologically protected edge modes.•Transitions BM–superinsulator and BM–superconductor are quantum BKT transitions. A low-temperature intervening metallic regime arising in the two-dimensional superconductor-insulator transition challenges our understanding of electronic fluids. Here we develop a gauge theory revealing that this emergent anomalous metal is a bosonic topological insulator where bulk transport is suppressed by mutual statistics interactions between out-of-condensate Cooper pairs and vortices and the longitudinal conductivity is mediated by symmetry-protected gapless edge modes. We explore the magnetic-field-driven superconductor-insulator transition in a niobium titanium nitride device and find marked signatures of a bosonic topological insulator behavior of the intervening regime with the saturating resistance. The observed superconductor-anomalous metal and insulator-anomalous metal dual phase transitions exhibit quantum Berezinskii-Kosterlitz-Thouless criticality in accord with the gauge theory.