[19a-B401-1~11] 11.1 Fundamental properties

△ [19a-B401-3] Two Antiferromagnetic phases surrounding high-T_c superconductivity in ¹⁵⁴SmFeAsO_1-xD_x

〇Soshi Iimura¹, Hiroshi Okanishi¹, Satoru Matsuishi², Haruhiro Hiraka³, Takashi Honda⁴, Kazutaka Ikeda⁴, Thomas Hansen⁵, Toshiya Otomo⁴, Hideo Hosono^1,2 (1.Tokyo Tech. MSL, 2.Tokyo Tech. MCES, 3.KAERI, 4.KEK, 5.ILL)

Keywords:iron-based superconductors, neutron scattering

We carried out neutron powder diffraction measurements on high-T_c iron-based superconductor ¹⁵⁴SmFeAsO_1-xD_x to construct the electronic phase diagram. First, we determined the structure of antiferromagnetic phase at x = 0 to be a conventional stripe-type order. In addition a new antiferromagnetic phase was discovered in the overdoped region for x > 0.5, where the magnetic moment on Fe site reached 2.7muB that is the highest value among all the iron arsenides superconductors. The unique phase diagram, i.e., highest-T_c superconducting phase adjacent to the strongly correlated phase in electron-overdoped regime, yields important clues to the unconventional origins of superconductivity.