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Superconductivity and possible variable range hopping in (TiZrNbCu)(1-x)Nix, (TiZrNbNi)(1-x)Cux and (TiZrNbCu)(1-x)Cox complex amorphous alloys

We present the result of a systematic study of electrical resistivity, superconductive transitions and Hall effect for three systems of compositionally complex amorphous alloys of early (TE) and late (TL) transition metals in a broad composition range x (0.1-0.5). All samples showed a high resistivity at room temperature (140-240 μΩ cm) and the superconducting transition temperatures decrease with increasing TL content, similar to binary amorphous [3] and crystalline HEA TE-TL alloys [4]. With the highest recorded transition for (TiZrNbCu)0.90Co0.10 at 1.94 K. The Hall coefficient RH is temperature independent and positive for all samples except for (TiZrNbCu)0.57Co0.43 with an interpolated critical concentration at xc=0.34, in good agreement with binary TE-TL alloys [1]. For the temperature dependence of resistivity, we discuss possible variable range hopping (VRH) like parallel conduction mode, in temperature range 30-150K, with an exponent p=1/2. We examine this in the context of VRH in granular materials [2]. References: [1] J. Ivkov and E. Babić, J. Phys.: Condens. Matter 2 (1990) 3891 [2] V. F. Gantmakher, Electrons and Disorder in Solids (OUP Oxford, 2005). [3] E. Babić et al, Solid State Commun. 39 (1981) 139 [4] K. Stolze et al, Chem. Mater. 30 (2018) 906

High entropy alloys ; Metallic glasses ; Hall effect ; Magnetotransport ; Superconductivity

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