Pseudo-gap in tunneling spectra as a signature of inhomogeneous superconductivity in oxide interfaces

Abstract

We present a theory for the pseudo-gap state recently observed at the LaAlO3/SrTiO3 interface, based on superconducting islands embedded in a metallic background. Superconductivity within each island is BCS-like, and the local critical temperatures are randomly distributed, some of them necessarily exceeding the critical temperature for global percolation to the zero resistance state. Consequently, tunneling spectra display a suppression of the density of states and coherence peaks already well above the percolative transition. This model of inhomogeneous superconductivity accounts well for the experimental tunneling spectra. The temperature dependence of the spectra suggests that a sizable fraction of the metallic background becomes superconducting by proximity effect when the temperature is lowered.

arXiv comment5 pages with 4 figures and supplementary material with 7 pages with 6 figures

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Cited by in corpus (8)

• Phase separation from electron confinement at oxide interfaces
• Evidence of weak superconductivity at the room-temperature grown LaAlO${}_3$/SrTiO${}_3$ interface
• Destruction of superconductivity through phase fluctuations in ultrathin a-MoGe films
• Electronic phase separation at LaAlO3/SrTiO3 interfaces tunable by oxygen deficiency
• Density inhomogeneities and Rashba spin-orbit coupling interplay in oxide interfaces
• Interplay between density and superconducting quantum critical fluctuations
• Competing electronic states emerging on polar surfaces
• Superfluid response of two-dimensional filamentary superconductors