Search for ferromagnetic order in overdoped copper-oxide superconductors
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Instrument and Source Division
- Yale Univ., New Haven, CT (United States). Applied Physics Dept.
- Brookhaven National Lab. (BNL), Upton, NY (United States); Yale Univ., New Haven, CT (United States). Applied Physics Dept.
In copper-oxides that show high-temperature superconductivity (HTS), the critical temperature (Tc) has a dome-shaped doping dependence. The cause of demise of both Tc and superfluid density ns on the overdoped side is a major puzzle. A recent study of transport and diamagnetism in a large number of overdoped La2-xSrxCuO4 (LSCO) films shows that this cannot be accounted for by disorder within the conventional Bardeen-Cooper-Schrieffer theory. This brings to focus an alternative explanation — competition of HTS with ferromagnetic order, fluctuating in superconducting samples and static beyond the superconductor-to-metal transition. Here, we examine this proposal by growing single-crystal LSCO thin films with doping on both sides of the transition by molecular beam epitaxy, and using polarized neutron reflectometry to measure their magnetic moments. In a heavily overdoped, metallic but non-superconducting LSCO (x = 0.35) film, the spin asymmetry of reflectivity shows a very small static magnetic moment (~2 emu/cm3). Less-doped, superconducting LSCO films show no magnetic moment in neutron reflectivity, both above and below Tc. Therefore, the collapse of HTS with overdoping is not caused by competing ferromagnetic order.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0012704; GBMF4410
- OSTI ID:
- 1351721
- Report Number(s):
- BNL-113691-2017-JA; R&D Project: MA509MACA; KC0203020
- Journal Information:
- Scientific Reports, Vol. 7; ISSN 2045-2322
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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journal | July 2018 |
Can high- T c superconductivity in cuprates be explained by the conventional BCS theory?
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journal | June 2018 |
Hall number, specific heat and superfluid density of overdoped high-Tc cuprates | preprint | January 2020 |
Scanning SQUID characterization of extremely overdoped $La_{2-x}Sr_{x}CuO_{4}$ | text | January 2021 |
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