Superconductivity in the Niobium-rich compound Nb5Se4

TL;DR

This study reports the synthesis and characterization of Nb5Se4, a niobium-rich selenide that exhibits superconductivity at 1.85K, with properties indicating it is a weak coupling BCS superconductor.

Contribution

The paper presents the first synthesis and detailed physical property analysis of Nb5Se4, establishing its superconducting nature and weak coupling characteristics.

Findings

Superconducting transition temperature T_c = 1.85K

Weak electron-phonon coupling with λ_ep = 0.5

Upper critical field of 1.44 T

Abstract

The niobium rich selenide compound Nb5Se4 was synthesized at ambient pressure by high-temperature solid-state reaction in a sealed Ta tube. Resistivity and heat capacity measurements reveal that this compound is superconducting, with a T_c = 1.85K. The electronic contribution to the specific heat {\gamma} and the Debye temperature are found to be 18.1 mJ/mol/K^2 and 298 K respectively. The calculated electron-phonon coupling constant {\lambda}_ep = 0.5 and the {\Delta}C_p/{\gamma}Tc = 1.42 ratio imply that Nb5Se4 is a weak coupling BCS superconductor. The upper critical field and coherence length are found to be 1.44 T and 15.1 nm, respectively.