Discovery of the Type-II Superconductor Ta${}_4$Rh${}_2$C${}_{1-\delta }$ with a High Upper Critical Field

Abstract

We report on the discovery of superconductivity in the previously unknown compound Ta${}_4$Rh${}_2$C${}_{1-\delta }$. Ta${}_4$Rh${}_2$C${}_{1-\delta }$ crystallizes in the $\eta$-carbide structure type, in the cubic space group $Fd\bar{3}m$ (No.227) with a unit cell parameter of $a=$ 11.7947 Å. Temperature-dependent magnetic susceptibility, resistivity, and specific heat capacity measurements reveal that Ta${}_4$Rh${}_2$C${}_{1-\delta }$ is a type-II bulk superconductor with a critical temperature of $T_{\mathrm{c}}$ = 6.4 K, and a normalized specific heat jump $\Delta C/\gamma T_{\mathrm{c}}$ = 1.56. Notably, we find Ta${}_4$Rh${}_2$C${}_{1-\delta }$ has a high upper critical field of ${\mu }_0{H}_{c2}(0)$ = 17.4 T, which is exceeding the BCS weak coupling Pauli limit of ${\mu }_0{H}_{\mathrm{Pauli}}$ = 11.9 T.

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Cited by in corpus (1)

• Structure, Composition, and High-Field Superconductivity in Metal-Rich $\eta$-Carbide-Type Compounds