Fermi surface and superconductivity in low-density high-mobility {\delta}-doped SrTiO3

TL;DR

This study explores the electronic structure and superconductivity in low-density SrTiO3 delta-doped heterostructures, revealing a dimensionality crossover and band degeneracy lifting through quantum oscillation measurements.

Contribution

It provides new insights into the Fermi surface evolution and superconducting properties as a function of dopant layer thickness in SrTiO3 heterostructures.

Findings

Observation of a crossover from 3D to 2D Fermi surface.

Detection of band degeneracy lifting due to subband quantization.

Distinct dimensionality crossover in superconducting versus normal states.

Abstract

The electronic structure of low-density n-type SrTiO3 delta-doped heterostructures is investigated by angular dependent Shubnikov-de Haas oscillations. In addition to a controllable crossover from a three- to two-dimensional Fermi surface, clear beating patterns for decreasing dopant layer thicknesses are found. These indicate the lifting of the degeneracy of the conduction band due to subband quantization in the two-dimensional limit. Analysis of the temperature-dependent oscillations shows that similar effective masses are found for all components, associated with the splitting of the light electron pocket. The dimensionality crossover in the superconducting state is found to be distinct from the normal state, resulting in a rich phase diagram as a function of dopant layer thickness.