Biscaras, J. and Bergeal, N. and Hurand, S. and Feuillet-Palma, C. and Rastogi, A. and Budhani, R. C. and Grilli, M. and Caprara, S. and Lesueur, J. (2013) Multiple quantum criticality in a two-dimensional superconductor. Nature Materials, 12 (6). pp. 542-548. ISSN 1476-1122

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The diverse phenomena associated with the two-dimensional electron gas (2DEG) that occurs at oxide interfaces include, among others, exceptional carrier mobilities, magnetism and superconductivity. Although these have mostly been the focus of interest for potential future applications, they also offer an opportunity for studying more fundamental quantum many-body effects. Here, we examine the magnetic-field-driven quantum phase transition that occurs in electrostatically gated superconducting LaTiO3/SrTiO3 interfaces. Through a finite-size scaling analysis, we show that it belongs to the (2 + 1)D XY model universality class. The system can be described as a disordered array of superconducting puddles coupled by a 2DEG and, depending on its conductance, the observed critical behaviour is single (corresponding to the long-range phase coherence in the whole array) or double (one related to local phase coherence, the other one to the array). A phase diagram illustrating the dependence of the critical field on the 2DEG conductance is constructed, and shown to agree with theoretical proposals. Moreover, by retrieving the coherence-length critical exponent nu, we show that the quantum critical behaviour can be clean or dirty according to the Harris criterion, depending on whether the phase-coherence length is smaller or larger than the size of the puddles.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s Nature Publishing Group.
Subjects: Chemistry > Physical Chemistry
Materials Science
Applied Physics/Condensed Matter
Depositing User: Users 27 not found.
Date Deposited: 09 Jul 2020 10:03
Last Modified: 09 Jul 2020 10:03

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