Pairing Symmetry and Upward Curvature of Upper Critical Field in Superconducting $N{a}_{0.35}Co{O}_2\cdot y{H}_{2}O$

Jun-Ting Kao, Jiunn-Yuan Lin, Chung-Yu Mou

The origin for the upward curvature of the upper critical field ($H_{c2}$) observed in hydrate cobaltate Na${}_{0.35}$CoO${}_2\cdot y$H${}_2$O is investigated based on the microscop…