Local electronic structures on the superconducting interface $LaAlO_{3}/SrTiO_{3}$

TL;DR

This paper theoretically studies the local electronic structures at the LaAlO3/SrTiO3 superconducting interface, revealing in-gap resonance peaks due to impurity scattering influenced by Rashba spin-orbit interaction, and explores how triplet pairing affects these features.

Contribution

It introduces a theoretical analysis of impurity effects and local density of states in the LaAlO3/SrTiO3 interface considering Rashba spin-orbit coupling, highlighting the mixed singlet-triplet superconducting state.

Findings

In-gap resonance peaks appear near impurities due to quasiparticle scattering.

The density of states evolves with the triplet pairing component influenced by RSOI.

The results can be observed in tunneling experiments on noncentrosymmetric superconductors.

Abstract

Motivated by the recent discovery of superconductivity on the heterointerface $LaAlO_{3}/SrTiO_{3}$, we theoretically investigate its local electronic structures near an impurity considering the influence of Rashba-type spin-orbit interaction (RSOI) originated in the lack of inversion symmetry. We find that local density of states near an impurity exhibits the in-gap resonance peaks due to the quasiparticle scattering on the Fermi surface with the reversal sign of the pairing gap caused by the mixed singlet and RSOI-induced triplet superconducting state. We also analyze the evolutions of density of states and local density of states with the weight of triplet pairing component determined by the strength of RSOI, which will be widely observed in thin films of superconductors with surface or interface-induced RSOI, or various noncentrosymmetric superconductors in terms of point contact tunneling and scanning tunneling microscopy, and thus reveal an admixture of the spin singlet and RSOI-induced triplet superconducting states.