Quantum Phase Transitions


Two-dimensional electron gases that occur at LaTiO3/SrTiO3 or LaAlO3/SrTiO3 oxide interfaces offer a unique opportunity to study quantum phase transitions in low-dimensionality electronic system. We have analyzed the magnetic-field-driven quantum phase transition that occurs in electrostatically gated superconducting oxide interfaces. Through a finite-size scaling analysis, we showed that it belongs to the (2+1)D XY model universality class. By varying the gate voltage we also studied the field-effect driven superconductor-to-metal quantum phase transition and showed that it displays an unusual critical exponents product (z-=3/2) which can be explained by density driven superconducting critical fluctuations.

Main references :

  • Phase Separation from Electron Confinement at Oxide Interfaces. N. Scopigno, D. Bucheli, S. Caprara, J. Biscaras, N. Bergeal, J. Lesueur, M. Grilli
    Phys. Rev. Lett. 116, 026804 (2016)
  • Interplay between density and superconducting quantum critical fluctuations. S Caprara, N. Bergeal, J. Lesueur and M. Grilli
    J. Phys. : Condens. Matter 27, 425701 (2015)
  • Multi-band superconductivity and nanoscale inhomogeneity at oxide interfaces , S. Caprara, J. Biscaras, N. Bergeal, D. Bucheli, S. Hurand, C. Feuillet-Palma, A. Rastogi, R. C. Budhani, J. Lesueur, M. Grilli
    Phys. Rev. B 88, 020504(R) (2013)
  • Multiple Quantum Phase Transitions at the superconducting LaTiO3/SrTiO3 interface, J. Biscaras, N. Bergeal, S. Hurand, C. Feuillet-Palma, A. Rastogi, R. C. Budhani, M. Grilli, S. Caprara, J. Lesueur
    Nature Mat. 12, 542 (2013)
  • Two-dimensional superconducting phase in LaTiO 3/SrTiO 3 heterostructures induced by high-mobility carrier doping, J. Biscaras, N. Bergeal, S. Hurand, C. Grossetete, A. Rastogi, R. C. Budhani, D. LeBoeuf, C. Proust, and J. Lesueur,
    Phys. Rev. Lett. 108, 247004 (2012)
  • Two-dimensional Superconductivity at a Mott-Insulator/Band-Insulator interface: LaTiO3 /SrTiO3, J. Biscaras, N. Bergeal, A.K. Kushwaha, T. Wolf, A. Gangawar, R.C. Budhani and J. Lesueur,
    Nature Commun. 1, 89 (2010)

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