Experimental evidence for a two-band superconducting state of NbSe2 single crystals

TL;DR

This study provides experimental evidence that NbSe2 single crystals exhibit a two-band superconducting state, with distinct anisotropic and isotropic bands influencing properties at different magnetic field strengths.

Contribution

The paper demonstrates that NbSe2's superconductivity is better explained by a two-band model rather than a single-band anisotropic model, revealing different behaviors in two distinct bands.

Findings

Superconductivity in NbSe2 is multi-band, not single-band.

Two bands have different anisotropies and dominate at different magnetic fields.

Method effectively distinguishes multi-band from single-band superconductivity.

Abstract

We report on measurements and a detailed analysis of the reversible magnetization of superconducting NbSe2 single crystals. By comparing the experimental data with Ginzburg Landau theory we show that superconductivity in NbSe2 cannot be explained by an anisotropic single-band, but by a multi-band scenario. Applying a simple two-band model reveals the basic mixed-state parameters, which are quite different in the two bands. We identify a strongly anisotropic band that determines the properties at high magnetic fields, and a second almost isotropic band that dominates at low fields. Our method is well suited for distinguishing anisotropic single-band from multi-band superconductivity in various materials.