Enhancement of superconductivity near the ferromagnetic quantum critical point in UCoGe.
We report a high-pressure single crystal study of the superconducting ferromagnet UCoGe. Measurements of the ac susceptibility and resistivity under pressures up to 2.2 GPa show ferromagnetism is smoothly depressed and vanishes at a critical pressure p(c) = 1.4 GPa. Near the ferromagnetic critical point superconductivity is enhanced. Upper-critical field measurements under pressure show B(c2)(0) attains remarkably large values, which provides solid evidence for spin-triplet superconductivity over the whole pressure range. The obtained p-T phase diagram reveals superconductivity is closely connected to a ferromagnetic quantum-critical point hidden under the superconducting "dome."
Van der Waals-Zeeman Institute, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands.
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Slooten
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Naka
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Gasparini
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Huang
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de Visser