Superconductivity with large upper critical field in noncentrosymmetric Cr-bearing high-entropy alloys

• DOI: 10.1016/j.scriptamat.2022.115099
• Publication Date: 2022-10-17T18:36:16Z
• Authors: Guorui Xiao; Wuzhang Yang; Qinqing Zhu; Shijie Song; Guang-Han Cao; Zhi Ren
• Keywords: Superconductivity (cond-mat.supr-con); Condensed Matter - Materials Science; Condensed Matter - Superconductivity; 0103 physical sciences; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; 02 engineering and technology; 0210 nano-technology; 01 natural sciences

8 pages, 5 figures<br/>A series of new Cr$_{5+x}$Mo$_{35-x}$W$_{12}$Re$_{35}$Ru$_{13}$C$_{20}$ high-entropy alloys (HEAs) have been synthesized and characterized by x-ray diffraction, scanning electron microscopy, electrical resistivity, magnetic susceptibility and specific heat measurements. It is found that the HEAs adopt a noncentrosymmetric cubic $β$-Mn type structure and exhibit bulk superconductivity for 0 $\leq$ $x$ $\leq$ 9. With increasing $x$, the cubic lattice parameter decreases from 6.7940(3) Å to 6.7516(3) Å. Meanwhile, the superconducting transition temperature $T_{\rm c}$ is suppressed from 5.49 K to 3.35 K due to the magnetic pair breaking caused by Cr moments. For all these noncentrosymmetric HEAs, the zero-temperature upper critical field $B_{\rm c2}$(0) is comparable to Pauli paramagnetic limit $B_{\rm P}$(0) = 1.86$T_{\rm c}$. In particular, the $B_{\rm c2}$(0)/$B_{\rm P}$(0) ratio reaches a maximum of $\sim$1.03 at $x$ = 6, which is among the highest for $β$-Mn type superconductors.<br/>