Pressure-induced unconventional superconductivity near a quantum critical point in CaFe2As2

S. Kawasaki; T. Tabuchi; X. F. Wang; X. H. Chen; Guo-qing Zheng

doi:10.1088/0953-2048/23/5/054004

Pressure-induced unconventional superconductivity near a quantum critical point in CaFe2As2

Superconductivity 2015-05-18 v2 Strongly Correlated Electrons

Authors: S. Kawasaki , T. Tabuchi , X. F. Wang , X. H. Chen , Guo-qing Zheng

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Abstract

75As-zero-field nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements are performed on CaFe2As2 under pressure. At P = 4.7 and 10.8 kbar, the temperature dependences of nuclear-spin-lattice relaxation rate (1/T1) measured in the tetragonal phase show no coherence peak just below Tc(P) and decrease with decreasing temperature. The superconductivity is gapless at P = 4.7 kbar but evolves to that with multiple gaps at P = 10.8 kbar. We find that the superconductivity appears near a quantum critical point under pressures in the range 4.7 kbar < P < 10.8 kbar. Both electron correlation and superconductivity disappear in the collapsed tetragonal phase. A systematic study under pressure indicates that electron correlations play a vital role in forming Cooper pairs in this compound.

Keywords

unconventional superconductivity quantum critical point pressure-induced CaFe2As2 nuclear magnetic resonance nuclear quadrupole resonance electron correlation multiple gaps

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@article{arxiv.1002.1114,
  title  = {Pressure-induced unconventional superconductivity near a quantum critical point in CaFe2As2},
  author = {S. Kawasaki and T. Tabuchi and X. F. Wang and X. H. Chen and Guo-qing Zheng},
  journal= {arXiv preprint arXiv:1002.1114},
  year   = {2015}
}

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Pressure-induced unconventional superconductivity near a quantum critical point in CaFe2As2

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