Year: 2025
Type: preprint
Abstract: Weak localization of bosons can give rise to an exotic quantum state known as a Bose glass, characterized by the absence of global phase coherence yet finite conductivity. Here, we report signatures of a Bose glass state in the weak localization regime of the ruthenium oxide Ca2RuO4 nanofilms. The electrical resistivity exhibits a characteristic logarithmic temperature dependence, ρ ~ ln(1/T), consistent with bosonic weak localization. Furthermore, β-function scaling analysis reveals a distinct “vertical flow,” indicating a qualitative change in scaling behavior associated with localized bosonic transport. These results suggest that signatures of Cooper pairs persist up to high temperatures of ~ 220 K. We identify two quantum critical points associated with changes in scaling behavior between the Bose glass and superconducting regimes, and between the Bose glass and strongly localized regimes. We demonstrate that the ground state is governed by the strength of localization arising from the interplay of electron correlation, lattice distortion of the RuO6 octahedra, and reduced dimensionality, where film thickness acts as an effective control parameter. These findings establish Ca2RuO4 nanofilms as a platform for exploring bosonic localization in strongly correlated oxides, with implications for cuprates and nickelates.
Source: arXiv (Cornell University)
Institution: Hokkaido University
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7084165242
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