# Indium substitution effect on the topological crystalline insulator family (Pb$_{1-x}$Sn$_{x}$)$_{1-y}$In$_{y}$Te: Topological and superconducting properties

## TL;DR

This study explores how indium substitution influences the structural, topological, and superconducting properties of (Pb,Sn)Te topological crystalline insulators, revealing a transition from metallic to insulating and superconducting states with increasing indium content.

## Contribution

It provides new insights into the effects of indium doping on the electronic phases and topological surface states in (Pb,Sn)Te TCIs, highlighting the emergence of superconductivity.

## Key findings

- Indium doping induces a transition from weak-metallic to insulating behavior.
- Superconductivity appears at higher indium levels with Tc up to 4.7 K.
- Indium modifies the bulk electronic structure, affecting topological surface states.

## Abstract

Topological crystalline insulators (TCIs) have been of great interest in the area of condensed matter physics. We investigated the effect of indium substitution on the crystal structure and transport properties in the TCI system (Pb$_{1-x}$Sn$_{x}$)$_{1-y}$In$_{y}$Te. For samples with a tin concentration $x\le50\%$, the low-temperature resisitivities show a dramatic variation as a function of indium concentration: with up to ~2% indium doping the samples show weak-metallic behavior, similar to their parent compounds; with ~6% indium doping, samples have true bulk-insulating resistivity and present evidence for nontrivial topological surface states; with higher indium doping levels, superconductivity was observed, with a transition temperature, Tc, positively correlated to the indium concentration and reaching as high as 4.7 K. We address this issue from the view of bulk electronic structure modified by the indium-induced impurity level that pins the Fermi level. The current work summarizes the indium substitution effect on (Pb,Sn)Te, and discusses the topological and superconducting aspects, which can be provide guidance for future studies on this and related systems.