Bose glass and Fermi glass

Korekiyo Takahashi*, Keiji Nakatsugawa, Masahito Sakoda, Yoshiko Nanao, Hiroyoshi Nobukane, Hideaki Obuse, Satoshi Tanda

*Corresponding author for this work

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It is known that two-dimensional superconducting materials undergo a quantum phase transition from a localized state to superconductivity. When the disordered samples are cooled, bosons (Cooper pairs) are generated from Fermi glass and reach superconductivity through Bose glass. However, there has been no universal expression representing the transition from Fermi glass to Bose glass. Here, we discovered an experimental renormalization group flow from Fermi glass to Bose glass in terms of simple β-function analysis. To discuss the universality of this flow, we analyzed manifestly different systems, namely a Nd-based two-dimensional layered perovskite and an ultrathin Pb film. We find that all our experimental data for Fermi glass fall beautifully into the conventional self-consistent β-function. Surprisingly, however, flows perpendicular to the conventional β-function are observed in the weakly localized regime of both systems, where localization becomes even weaker. Consequently, we propose a universal transition from Bose glass to Fermi glass with the new two-dimensional critical sheet resistance close to R□=h/e2.
Original languageEnglish
Article number12434
Number of pages9
JournalScientific Reports
Issue number1
Publication statusPublished - 1 Aug 2023


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