Abstract
When a pure material is tuned to the point where a continuous phase-transition line is crossed at zero temperature, known as a quantum critical point (QCP), completely new correlated quantum ordered states can form1,2,3,4,5,6,7. These phases include exotic forms of superconductivity. However, as superconductivity is generally suppressed by a magnetic field, the formation of superconductivity ought not to be possible at extremely high field8. Here, we report that as we tune the ferromagnet, URhGe, towards a QCP by applying a component of magnetic field in the material’s easy magnetic plane, superconductivity survives in progressively higher fields applied simultaneously along the material’s magnetic hard axis. Thus, although superconductivity never occurs above a temperature of 0.5 K, we find that it can survive in extremely high magnetic fields, exceeding 28 T.
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Acknowledgements
Financial support was provided for work at the GHMFL from the European Commission. A.H. gratefully acknowledges support from the Royal Society, UK.
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Lévy, F., Sheikin, I. & Huxley, A. Acute enhancement of the upper critical field for superconductivity approaching a quantum critical point in URhGe. Nature Phys 3, 460–463 (2007). https://doi.org/10.1038/nphys608
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DOI: https://doi.org/10.1038/nphys608