Superconductivity in Cubic A15-type V–Nb–Mo–Ir–Pt High-Entropy Alloys

Bin Liu,Jifeng Wu,Yanwei Cui,Guanghan Cao,Qinqing Zhu,Zhi Ren,Guorui Xiao,Siqi Wu

doi:10.3389/fphy.2021.651808

Abstract

We report the crystal structure and superconducting properties of new V5+2xNb35−xMo35−xIr10Pt15 high-entropy alloys (HEAs) for x in the range of 0 ≤x≤ 10. These HEAs are found to crystallize in a cubic A15-type structure and have a weakly coupled, fully gapped superconducting state. A maximum Tc of 5.18 K and zero-temperature upper critical field Bc2(0) of 6.4 T are observed at x = 0, and both quantities decrease monotonically with the increase of V content x. In addition, Tc shows an increase with increasing valence electron concentration from 6.4 to 6.5, which is compared with other A15-type HEA and binary superconductors.

Highlights

High-entropy alloys (HEAs) consisting of five or more constituent elements have received a lot of attention as an emerging class of multicomponent alloys [1,2,3,4,5]
Physical property measurements indicate that these A15-type high-entropy alloys (HEAs) are weakly coupled, fully gapped superconductors with Tc and Bc2 (0) up to 5.18 K and 6.4 T, respectively. Their Tc increases with increasing valence electron concentrations (VECs), in contrast to the V–Nb–Mo–Al–Ga HEAs
The phase purity of as-cast HEAs was checked by powder x-ray diffraction (XRD) at room temperature using a Bruker D8 Advance x-ray diffractometer with Cu-Kα radiation

Summary

Introduction

High-entropy alloys (HEAs) consisting of five or more constituent elements have received a lot of attention as an emerging class of multicomponent alloys [1,2,3,4,5]. These alloys are stabilized by the high mixing entropy rather than the formation enthalpy, and often refereed to as metallic glasses on ordered lattices. The A15-type V1.4Nb1.4Mo0.2Al0.5Ga0.5 HEA has a Tc of 10.2 K and a disorder-enhanced upper critical field of 20.1 T [18], both of which are the highest among HEA superconductors. Since the VEC of the V–Nb–Mo–Al–Ga HEAs is limited below around 5, it is desirable to search for other A15-type HEA superconductors with VEC close to 6.5

Methods

Results

Conclusion