Phase diagram of compressed RbEuFe<sub>4</sub>As<sub>4</sub> and CsEuFe<sub>4</sub>As<sub>4</sub>: Coexistence of superconductivity and magnetism
ORAL
Abstract
RbEuFe4As4 and CsEuFe4As4 are members of the recently discovered 1144 superconducting family, they exhibit the unusual combination of superconductivity (Tc ~ 35 K) and ferromagnetism (Tm ~ 15 K). We performed a series of measurements under compression including x-ray diffraction, magnetic susceptibility, and electrical resistivity. Compression monotonically suppresses Tc and enhances Tm. Near 7 GPa, Tc onset and Tm become comparable, at higher compression evidence of bulk superconductivity gradually disappears. Room-temperature x-ray diffraction measurements provide evidence of a transition from tetragonal to a half-collapse-tetragonal structure near 10 GPa for RbEuFe4As4 and near 12 GPa for CsEuFe4A4. The cross-over from ferromagnetic superconductor (Tc > Tm), to superconducting ferromagnet (Tm > Tc) occurs before the structural transition, suggesting that RbEuFe4As4 and CsEuFe4As4 are an ideal system for studying the interplay between superconductivity and magnetism.
*Equipment development partially supported by the NHMFL User Collaboration Grants Program, NSF Cooperative Agreement DMR-1157490 and the State of Florida, as well as DOE-NNSA DE-NA0002928. Measurements supported by NSF DMR-1453752, NSF EAR-1606856, and DFG MA 7362/1-1. DEJ aknowledges support from LDRD XWR500.
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Presenters
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Daniel Jackson
- Pulsed Field Facility, National High Magnetic Field Laboratory, Los Alamos National Lab