Superconductivity in equimolar Nb-Re-Hf-Zr-Ti high entropy alloy

Herein, we report the synthesis and detailed superconducting properties of a new high entropy alloy superconductor with nominal composition Nb20Re20Zr20Hf20Ti20 using powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), magnetization, transport, and thermodynamic measurements. The room temperature powder XRD confirms that the alloy is arranged on a simple body-centered cubic crystal lattice with lattice parameter a = 3.38 (1) angstrom. EDX measurement yields an average composition of Nb21Re16Zr20Hf23Ti20 (in atomic %). Transport, magnetic and heat capacity measurements reveal that the material is a type-II superconductor with the bulk superconducting transition at T-c = 5.3 K, lower critical field H-c1 (0) = 33 mT and upper critical field H-c2(0) = 8.88 T. Low - temperature specific heat measurement indicates that the sample is a moderately coupled superconductor, and the electronic specific heat data fits well with the single-gap BCS model. (C) 2018 Elsevier B.V. All rights reserved.