Unusual magnetic field-induced phase transition in the mixed state of superconducting NbSe2

TL;DR

This study reports an unusual, hysteretic magnetic field-induced phase transition in the thermal conductivity of NbSe2, suggesting a first-order phase transition in its superconducting mixed state, with the transition's origin remaining unclear.

Contribution

It reveals a novel magnetic field-induced phase transition in NbSe2's superconducting state, characterized by hysteresis in thermal conductivity measurements.

Findings

Hysteretic behavior of thermal conductivity observed in specific magnetic field orientations.

The phase transition exhibits features of a first-order transition.

The transition's origin remains unidentified.

Abstract

The thermal conductivity \kappa in the basal plane of single-crystalline hexagonal NbSe2 has been measured as a function of magnetic field H, oriented both along and perpendicular to the c-axis, at several temperatures below T_c. With the magnetic field in the basal plane and oriented parallel to the heat flux we observed, in fields well below H_c2, an unexpected hysteretic behavior of \kappa(H) with all the generic features of a first order phase transition. The transition is not manifest in the \kappa(H) curves, if H is still in the basal plane but oriented perpendicularly to the heat-flux direction. The origin of the transition is not yet understood.