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

• Published in: Journal of alloys and compounds 2018-11, Vol.769, p.1059-1063
• Main Authors: Marik, Sourav, Varghese, Maneesha, Sajilesh, K.P., Singh, Deepak, Singh, R.P.
• Format: Article
• Language: English
• Subjects: Alloys; Body centered cubic lattice; Composition; Critical field (superconductivity); Crystal lattices; Energy dispersive X ray spectroscopy; Entropy; Hafnium base alloys; Heat measurement; High entropy alloy; High entropy alloys; Scientific imaging; Specific heat; Superconductivity; Transport; X ray powder diffraction; X ray spectra; X-ray diffraction; Zirconium
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.08.039

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) Å. 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 Tc  = 5.3 K, lower critical field Hc1 (0) = 33 mT and upper critical field Hc2(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. [Display omitted] •Detailed superconducting properties of a new high entropy alloy superconductor Nb20Re20Zr20Hf20Ti20 were studied.•The material is a type-II moderately coupled single-gap BCS superconductor.•Superconducting transition temperature TC = 5.3 K and lower critical field HC1(0) = 33 mT.•The obtained value of the upper critical field HC2(0) (8.88 T) is close to the Pauli limiting field.