Two-dimensional electron gas at oxides interfaces


Transition metal oxides have attracted much attention in recent decades for the richness of their phase diagrams that reveal a variety of electronic properties ranging from high-Tc superconductivity to colossal magnetoresistance. As these materials have comparable lattice parameters, they can be combined artificial heterostructures with atomically flat interface, which provides unique opportunities for the generation of novel emergent properties and functionalities. In this context, the discovery of a superconducting two-dimensional electron gas at the interface between two insulating oxides such as LaAlO3 and SrTiO3 has generated a considerable interest. In these heterostructures, the 2-DEG is confined in an interfacial quantum well that extends to approximately 10 nm into the SrTiO3 substrate at low temperature. The superconducting transition temperature Tc can be tuned over a wide range by means of electrostatic gating, which allows a superconducting phase diagram of this interface to be derived. The breaking of translational symmetry in the interfacial quantum well also generates a spin-orbit coupling of Rashba type, whose strength can be tuned by a gate voltage.
The PHASME team studies the properties of these electronic systems by dc and microwave low-temperature electronic transport.

Main references :

  • Gap suppression at a Lifshitz transition in a multi-condensate superconductor G. Singh1, A. Jouan, G. Herranz, M. Scigaj, F. Sanchez, L. Benfatto, S. Caprara, M. Grilli, F. Couedo, C. Feuillet-Palma, J. Lesueur, N. Bergeal
    Nature Mat. 18, 948–954 (2019)
  • Josephson-like dynamics of the superconducting LaAlO3/SrTiO3 interface. S. Hurand, A. Jouan, E. Lesne, G. Singh, C. Feuillet-Palma, M. Bibes, A. Barthélémy, J. Lesueur & N. Bergeal
    Phys. Rev. B. 99, 104515 (2019)
  • Competition between electron pairing and phase coherence in superconducting interfaces G. Singh, A. Jouan, L. Benfatto, F. Couedo, P. Kumar, A. Dogra, R. Budhani, S. Caprara, M. Grilli, E. Lesne, A. Barthelemy, M. Bibes, C. Feuillet-Palma, J. Lesueur, N. Bergeal
    Nature Commun. 5,407 (2018)
  • Effect of disorder on superconductivity and Rashba spin-orbit coupling in LaAlO3/SrTiO3 interfaces G. Singh, A. Jouan, S. Hurand, C. Palma, P. Kumar, A. Dogra, R. Budhani, J. Lesueur and N. Bergeal
    Phys. Rev. B 96, 024509 (2017)
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    Appl. Phys. Lett. 108, 052602 (2016)
  • Engineering 2D-superconductivity and Rashba spin-orbit coupling by selective orbital occupancy G. Herranz, G. Singh, N. Bergeal, A. Jouan, J. Lesueur, J. Gazquez, M. Varela, M. Scigaj, N. Dix, F. Sanchez and J. Fontcuberta
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  • 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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