High upper critical field (120 T) with small anisotropy of highly hydrogen-substituted SmFeAsO epitaxial film
Kota Hanzawa, Jumpei Matsumoto, Soshi Iimura, Yoshimitsu Kohama, Hidenori Hiramatsu, Hideo Hosono
Abstract
The electronic transport properties of a highly hydrogen-substituted 1111-type SmFeAsO epitaxial film with high critical-temperature $({T}_{\mathrm{c}}=45\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ were investigated under high magnetic fields. By using a single-turn magnet generating up to 130 T, we clarified that the upper critical field $({\ensuremath{\mu}}_{0}{H}_{\mathrm{c}2})$ of $\mathrm{SmFeAs}{\mathrm{O}}_{0.65}{\mathrm{H}}_{0.35}$ is 120 T at the nearly low-temperature limit of 2.2 K for ${\ensuremath{\mu}}_{0}H\ensuremath{\parallel}ab$. The angular dependence of ${\ensuremath{\mu}}_{0}{H}_{\mathrm{c}2}$ revealed that the anisotropic parameter $(\ensuremath{\gamma})$ around ${T}_{\mathrm{c}}$ is $\ensuremath{\sim}2$, which is comparable with that of a practical candidate 122-type $\mathrm{Ba}{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$ with lower ${T}_{\mathrm{c}}$ and much smaller than that of F-substituted SmFeAsO. The small $\ensuremath{\gamma}$ mainly originates from the high hydrogen incorporation. The extremely high ${\ensuremath{\mu}}_{0}{H}_{\mathrm{c}2}$ and small $\ensuremath{\gamma}$, together with the high ${T}_{\mathrm{c}}$ and high critical current density, suggest that $\mathrm{SmFeAs}{\mathrm{O}}_{1\ensuremath{-}x}{\mathrm{H}}_{x}$ has high potential for the superconducting electromagnets and cables.