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Superconductivity in the superhard boride WB 4.2

2018; IOP Publishing; Volume: 31; Issue: 11 Linguagem: Inglês

10.1088/1361-6668/aade5a

1361-6668

Elizabeth M. Carnicom, Judyta Strychalska‐Nowak, Piotr Wiśniewski, D. Kaczorowski, Weiwei Xie, Tomasz Klimczuk, R. J. Cava,

Iron-based superconductors research

We show that the superhard boride WB$_{4.2}$ is a superconductor with a T$_c$ of 2.05(5) K. Temperature-dependent magnetic susceptibility, electrical resistivity, and specific heat measurements were used to characterize the superconducting transition. The Sommerfeld constant {\gamma} for WB$_{4.2}$ is 2.07(3) mJ mol$^{-1}$ K$^{-2}$ and the {\Delta}C/{\gamma}T$_c$ = 1.56, which is somewhat higher than what is expected for weakly coupled BCS type superconductors. The H$_{c2}$ vs T plot is linear over a wide temperature range but does show signs of flattening by the lowest temperatures studied and therefore the zero-temperature upper critical field ({\mu}$_0$H$_{c2}$(0)) for WB$_{4.2}$ lies somewhere between the linear extrapolation of {\mu}$_0$H$_{c2}$(T) to 0 K and expectations based on the WHH model.