Disorder-Induced Universalily of Hole-doped 122-Type Pnictide Superconductors Phase Diagrams
ORAL
Abstract
Unconventional superconductivity in iron-based pnictides is induced by the suppression of a universal spin density wave ground state (SDW) in which the magnetic moments are AFM aligned in the ab plane. Several hole-doped family members were shown to exhibit reentrance, at different doping, to a C4 magnetic phase with spin reorientation to the out-of-plane direction. The discovery of this phase near superconductivity provided insights into the competing mechanisms underlying their complex phase diagrams but the conditions under which it is stabilized are not well understood. Here, we report the results of a comprehensive study of hole-doped materials as a function of ionic size and dopant concentration. We find that the C4 phase is confined to regions in which the As-Fe-As bond angle is close to that of a perfect tetrahedron and that the TN's of the SDW and C4 phases are linked by a scaling equation consistent with a common origin as itinerant nesting instabilities. Furthermore, we show that all the SDW and C4 transition temperatures collapse onto a universal phase diagram when the hole concentrations are scaled to the C4 dome which represent the amount of disorder.
*Work supported by the U.S. DOE, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division
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Presenters
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Omar Chmaissem
- Physics, Northern Illinois University
- Physics, Northern Illinois University, Material Science Division, Argonne National Lab
- Northern Illinois University
- Physics (NIU) and Material Science Division (ANL), Northern Illinois University