Distinctive doping dependence of upper critical field in iron-based superconductor LaFeAsO1−xHx

High magnetic fields up to 105 T have been utilized in deriving the upper critical field ${B}_{\mathrm{c}2}$ of ${\mathrm{LaFeAsO}}_{1\ensuremath{-}x}{\mathrm{H}}_{x}$ throughout the wide temperature range below ${T}_{\mathrm{c}}$. Resistivity measurements demonstrate that ${B}_{\mathrm{c}2}$ behaves differently in samples with $x=0.12$ (SC1) from those with 0.32 (SC2). In SC1, the two-band model assuming $s$-wave pairing gives a good fitting with a repulsive intraband interaction and dominant interband coupling. In SC2, we have to assume an attractive intraband interaction with weak interband coupling, which in fact suggests a non-$s$-wave pairing in view of the strong Coulomb repulsion. These results support the possibility that SC1 and SC2 have different pairing symmetries.