New antiferromagnetic phase: Clue to design of iron-based superconductor with higher critical temperature

Researcher group led by Hideo Hosono (Soshi Iimura, Hiroshi Okanishi, and Satoru Matsuishi) at Tokyo Institute of Technology has disclosed a unique phase diagram yields important clues to the unconventional origins of high-T_c superconductivity.

In iron-based superconductors, high critical temperature (T_c) superconductivity over 50 K has only been accomplished in electron-doped hREFeAsO (hRE is heavy rare earth (RE) element). Although hREFeAsO has the highest bulk T_c (58 K), progress in understanding its physical properties has been relatively slow due to difficulties in achieving high-concentration electron doping and carrying out neutron experiments. Here, the researchers present a systematic neutron powder diffraction study of ¹⁵⁴SmFeAsO _1-xD_x, and the discovery of a long-range antiferromagnetic ordering with x ≥ 0.56 (AFM2) accompanying a structural transition from tetragonal to orthorhombic. Surprisingly, the Fe magnetic moment in AFM2 reaches a magnitude of 2.73 μ_B/Fe, which is the largest in all nondoped iron pnictides and chalcogenides. Theoretical calculations suggest that the AFM2 phase originates in kinetic frustration of the Fe-3d_xy orbital, in which the nearest-neighbor hopping parameter becomes zero. 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.

This research result was published on the early edition of Proceedings of the National Academy of Sciences of the United States of America on May 15th, 2017.

Reference

Authors:	Soshi Iimuraa,*, Hiroshi Okanishia, Satoru Matsuishib,Haruhiro Hirakac, Takashi Hondad, Kazutaka Ikedad, Thomas C. Hansene, Toshiya Otomod,f, and Hideo Hosonoa,b,*
Title of original paper:	Large-moment antiferromagnetic order in overdoped high-Tc superconductor 154SmFeAsO1-xDx
Journal:	Proceedings of the National Academy of Sciences of the United States of America
DOI :	10.1073/pnas.1703295114
Affiliations :	a Laboratory for Materials and Structures, Tokyo Institute of Technology b Material Research Center for Element Strategy, Tokyo Institute of Technology c Graduate School of Science and Engineering, Ibaraki University d Institute of Materials Structure Science, High Energy Accelerator Research Organization e Institut Laue-Langevin f Department of Materials Structure Science, The Graduate University for Advanced Studie

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• Hosono-Kamiya Laboratory
• Researcher Profile | Tokyo Tech STAR Search - Soshi Iimura
• Researcher Profile | Tokyo Tech STAR Search - Satoru Matsuishi
• Researcher Profile | Tokyo Tech STAR Search - Hideo Hosono
• Materials Research Center for Element Strategy
• Laboratory for Materials and Structures
• Institute of Innovative Research (IIR)
• Department of Materials Science and Engineering, School of Materials and Chemical Technology
• Graduate School of Science and Engineering | Academics | Ibaraki University
• Institute of Materials Structure Science, High Energy Accelerator Research Organization
• Institut Laue-Langevin
• School of High Energy Accelerator | The Graduate University for Advanced Studies
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