Superconductivity in equimolar Nb-Re-Hf-Zr-Ti high entropy alloy (1804.10092v1)

Abstract: Herein, we report the synthesis and detailed superconducting properties of a new high entropy alloy superconductor with nominal composition Nb${20}$Re${20}$Zr${20}$Hf${20}$Ti${20}$ 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) $\text{\AA}$. EDX measurement yields an average composition of Nb${21}$Re${16}$Zr${20}$Hf${23}$Ti${20}$ (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.