Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1516834 | Journal of Physics and Chemistry of Solids | 2011 | 4 Pages |
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 10.8Â kbar, the temperature dependence of nuclear-spin-lattice relaxation rate (1/T1) measured at tetragonal phase show no coherence peak just below Tc and decrease with decreasing temperature. The superconductivity is of gapless at P=4.7Â kbar but evolves to multiple gaps at P=10.8Â kbar. We find that the superconductivity appears near a quantum critical point. 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.
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Authors
S. Kawasaki, T. Oka, T. Tabuchi, X.F. Wang, X.H. Chen, Guo-qing Zheng,