Bulk electronic state of superconducting topological insulator

TL;DR

This paper investigates the electronic properties of superconducting topological insulators, focusing on how different pairing symmetries affect measurable quantities like specific heat and spin susceptibility, proposing a method to identify pairing symmetry via Knight shift measurements.

Contribution

It provides a detailed analysis of temperature-dependent specific heat and spin susceptibility for various pairing symmetries, suggesting a practical way to determine pairing symmetry through Knight shift experiments.

Findings

Specific heat temperature dependence is similar across three pairings.

Spin susceptibility varies significantly with pairing symmetry.

Knight shift measurement can identify the pairing symmetry.

Abstract

We study electronic properties of a superconducting topological insulator whose parent material is a topological insulator. We calculate the temperature dependence of the specific heat and spin susceptibility for four promising superconducting pairings proposed by L. Fu and E. Berg (Phys. Rev. Lett. 105, 097001). Since the line shapes of temperature dependence of specific heat are almost identical among three of the four pairings, it is difficult to identify them simply from the specific heat. On the other hand, we obtain wide varieties of the temperature dependence of spin susceptibility for each pairing reflecting the spin structure of Cooper pair. We propose that the pairing symmetry of superconducting topological insulator can be determined from measurement of Knight shift by changing the direction of applied magnetic field.