We report the single crystal growth and characterization of the highest Tc
iron-based superconductor SmFeAsO1-xHx. Some sub-millimeter-sized crystals were
grown using the mixture flux of Na3As + 3NaH + As at 3.0 GPa and 1473 K. The
chemical composition analyses confirmed 10% substitution of hydrogen for the
oxygen site (x = 0.10), however, the structural analyses suggested that the
obtained crystal forms a multi-domain structure. By using the FIB technique we
fabricated the single domain SmFeAsO0.9H0.10 crystal with the Tc of 42 K, and
revealed the metallic conduction in in-plane (rhoab), while semiconducting in
the out-of-plane (rhoc). From the in-plane Hall coefficient measurements, we
confirmed that the dominant carrier of SmFeAsO0.9H0.10 crystal is an electron,
and the hydride ion occupied at the site of the oxygen ion effectively supplies
a carrier electron per iron following the equation: O2- = H- + e-.Comment: 4 figures, 2 table
