Enhancement of Superconductivity in WP via Oxide-Assisted Chemical Vapor Transport

TL;DR

This paper shows that a new method for growing WP crystals enhances superconductivity and changes its properties.

Contribution

A new chemical vapor transport method for WP growth increases superconducting transition temperature and reduces scattering.

Findings

WP crystals grown via CVT show superconducting transitions above 1 K, higher than the previously reported 0.8 K.

The new method reduces low-temperature scattering and promotes a more three-dimensional crystal structure.

Variation in Tc suggests possible unconventional pairing or competing orders in WP.

Abstract

Tungsten monophosphide (WP) has been reported to superconduct below 0.8 K, and theoretical work has predicted an unconventional Cooper pairing mechanism. Here we present data for WP single crystals grown by means of chemical vapor transport (CVT) of WO3, P, and I2. In comparison to synthesis using WP powder as a starting material, this technique results in samples with substantially decreased low-temperature scattering and favors a more three-dimensional morphology. We also find that the resistive superconducting transitions in these samples begin above 1 K. Variation in Tc is often found in strongly correlated superconductors, and its presence in WP could be the result of influence from a competing order and/or a non-s-wave gap.

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