Abstract
The pressure dependence of the upper critical field, , of single crystalline FeSe was studied using measurements of the interplane resistivity, , in magnetic fields parallel to tetragonal axis. curves obtained under hydrostatic pressures up to GPa, the range over which the superconducting transition temperature, , of FeSe exhibits a nonmonotonic dependence with local maximum at GPa and local minimum at GPa. The slope of the upper critical field at , also exhibits a nonmonotonic pressure dependence with distinct changes at and . For the slope can be described within a multiband orbital model. For both and the slope is in good semiquantitative agreement with a single band, orbital Helfand-Werthamer theory with Fermi velocities determined from Shubnikov–de Haas measurements. This finding indicates that Fermi surface changes are responsible for the local minimum of at GPa.
- Received 27 November 2015
- Revised 8 January 2016
DOI:https://doi.org/10.1103/PhysRevB.93.064503
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