Charge Density Wave Order in Superconducting Topological Insulator Nbx-Bi2Se3

TL;DR

This paper presents evidence of charge density wave order coexisting with superconductivity in Nb-intercalated Bi2Se3, highlighting the role of lattice distortions and anisotropy in this topological superconductor.

Contribution

It reports the experimental observation of charge density wave order in Nb-Bi2Se3, a phenomenon not previously documented in this material.

Findings

Evidence of charge density wave and superconductivity coexistence

Intercalation-induced lattice distortion stabilizes CDW

Anisotropic electronic and phonon properties observed

Abstract

Spontaneously broken symmetry in the ground state of Bi-based topological materials can lead to promising Topological superconductors, such as Cu-Bi2Se3, Sr-Bi2Se3 and Nb-Bi2Se3. In recent studies, coexistence of multiple Fermi surface features and superconductivity was found in Nb-Bi2Se3. However, the resultant mutliple Fermi surface--charge density wave has not been experimentally reported yet. In this paper, we report possible evidence of co-occurence of a charge density wave (CDW) ground state and a superconducting (SC) ground state in Nb intercalated Bi2Se3. An intercalation induced Periodic Lattice Distortion appears to help stabilize the CDW state, possibly assisting in the formation of 1D chains and rendering electronic and phonon anisotropy to this intriguing system.