Sun J P, Jiao Y Y, Yang C L, Wu W, Yi C J, Wang B S, Shi Y G, Luo J L, Uwatoko Y, Cheng J-G
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
J Phys Condens Matter. 2017 Nov 15;29(45):455603. doi: 10.1088/1361-648X/aa8c94. Epub 2017 Oct 19.
KCrAs is a newly discovered quasi-1D superconductor with a T = 6.1 K and an upper critical field µ H (0) ≈ 40 T three times larger than the Pauli paramagnetic limit µ H that is suggestive of a spin-triplet Cooper pairing. In this paper, we have investigated the effects of hydrostatic pressure on its T and µ H by measuring the ac magnetic susceptibility χ'(T) under magnetic fields at various hydrostatic pressures up to 7.5 GPa. The major findings include: (1) T is suppressed gradually to below 2 K at 7.5 GPa; (2) the estimated µ H (0) decreases dramatically to below µ H above ~2 GPa and becomes slight lower than the orbital limiting field [Formula: see text] estimated from the initial slope of upper critical field via [Formula: see text] = -0.73T dH /[Formula: see text] in the clean limit; (3) the estimated Maki parameter α = √2[Formula: see text]/H drops from 4 at ambient pressure to well below 1 at P > 2 GPa, suggesting the crossover from Pauli paramagnetic limiting to orbital limiting in the pair breaking process upon increasing pressure. These observations suggested that the application of hydrostatic pressure could drive KCrAs away from the ferromagnetic instability and lead to a breakdown of the spin-triplet pairing channel. We have also made a side-by-side comparison and discussed the distinct effects of chemical and physical pressures on the superconducting properties of KCrAs.
