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As-NMR/NQR study of pressure-induced superconductivity in CaFe2As2 |
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| Authors: | S Kawasaki T Oka XF Wang Guo-qing Zheng |
| Institution: | a Department of Physics, Okayama University, Okayama 700-8530, Japan b Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China c Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China |
| 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 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=4.7 kbar but evolves to multiple gaps at P=10.8 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. |
| Keywords: | D Nuclear magnetic resonance D Nuclear quadrupole resonance D Superconductivity |
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