Specific heat and electronic states of superconducting boron-doped silicon carbide

TL;DR

This study investigates the specific heat and electronic structure of boron-doped silicon carbide, revealing unique superconducting properties and differences from related boron-doped semiconductors, with implications for understanding superconductivity in doped materials.

Contribution

It provides the first detailed specific heat analysis and electronic structure insights for boron-doped silicon carbide, highlighting its distinct superconducting behavior.

Findings

Quadratic temperature dependence of electronic specific heat in superconducting state

Possible nodal gap structure or residual density of states

Comparison of superconducting parameters with related materials

Abstract

The discoveries of superconductivity in the heavily-boron doped semiconductors diamond (C:B) in 2004 and silicon (Si:B) in 2006 have renewed the interest in the physics of the superconducting state of doped semiconductors. Recently, we discovered superconductivity in the closely related ''mixed'' system heavily boron-doped silcon carbide (SiC:B). Interestingly, the latter compound is a type-I superconductor whereas the two aforementioned materials are type-II. In this paper we present an extensive analysis of our recent specific-heat study, as well as the band structure and expected Fermi surfaces. We observe an apparent quadratic temperature dependence of the electronic specific heat in the superconducting state. Possible reasons are a nodal gap structure or a residual density of states due to non-superconducting parts of the sample. The basic superconducting parameters are estimated in a Ginzburg-Landau framework. We compare and discuss our results with those reported for C:B and Si:B. Finally, we comment on possible origins of the difference in the superconductivity of SiC:B compared to the two ''parent'' materials C:B and Si:B.