title: Chern structure in the Bose-insulating phase of Sr2RuO4nanofilms.
abstract: The quantum anomaly that breaks the symmetry, for example the parity and the chirality, in the quantization leads to a physical quantity with a topological Chern invariant. We report the observation of a Chern structure in the Bose-insulating phase of Sr2RuO4nanofilms by employing electric transport. We observed the superconductor-to-insulator transition by reducing the thickness of Sr2RuO4single crystals. The appearance of a gap structure in the insulating phase implies local superconductivity. Fractional quantized conductance was observed without an external magnetic field. We found an anomalous induced voltage with temperature and thickness dependence, and the induced voltage exhibited switching behavior when we applied a magnetic field. We suggest that there was fractional magnetic-field-induced electric polarization in the interlayer. These anomalous results are related to topological invariance. The fractional axion angle Θ = π/6 was determined by observing the topological magneto-electric effect in the Bose-insulating phase of Sr2RuO4nanofilms.
authors.affiliation: Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan.|Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Nobukane
authors.affiliation: Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan.|Department of Physics, Nara University of Education, Nara 630-8528, Japan.
authors.forename: Toyoki
authors.initials: T
authors.lastname: Matsuyama
authors.affiliation: Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo, 060-8628, Japan.|Department of Applied Physics, Hokkaido University, Sapporo 060-8628, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanda