Materials Science and Engineering News

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

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May 26, 2017

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-Tc superconductivity.

In iron-based superconductors, high critical temperature (Tc) 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 Tc (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-xDx, 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 μB/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-3dxy orbital, in which the nearest-neighbor hopping parameter becomes zero. The unique phase diagram, i.e., highest-Tc 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.

Electronic phase diagram of SmFeAsO1-xHx.

Figure. Electronic phase diagram of SmFeAsO1-xHx.


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.1703295114Outer
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

Further information

Assistant Professor Soshi Iimura
Laboratory for Material and Structure, Institute of Innovative Research, Tokyo Institute of Technology

Tel +81-45-924-5134

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