Nonmonotonic pressure evolution of the upper critical field in superconducting FeSe

作者：Kaluarachchi Udhara S^*; Taufour Valentin; Boehmer Anna E; Tanatar Makariy A; Bud'ko Sergey L; Kogan Vladimir G; Prozorov Ruslan; Canfield Paul C

来源：PHYSICAL REVIEW B, 2016, 93(6): 064503.

DOI：10.1103/PhysRevB.93.064503

The pressure dependence of the upper critical field, H-c2,H-c, of single crystalline FeSe was studied using measurements of the interplane resistivity, rho(c), in magnetic fields parallel to tetragonal c axis. H-c2,H-c(T) curves obtained under hydrostatic pressures up to 1.56 GPa, the range over which the superconducting transition temperature, T-c, of FeSe exhibits a nonmonotonic dependence with local maximum at p(1) approximate to 0.8 GPa and local minimum at p(2) approximate to 1.2GPa. The slope of the upper critical field at T-c, (dH(c2,c)/dT)T-c, also exhibits a nonmonotonic pressure dependence with distinct changes at p(1) and p(2). For p < p(1) the slope can be described within a multiband orbital model. For both p(1) < p < p(2) and p > p(2) 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 T-c(p) at p(2) approximate to 1.2 GPa.

• 出版日期2016-2-1