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arXiv · 1002.1114

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

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.

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S. Kawasaki, T. Tabuchi, X. F. Wang, X. H. Chen, Guo-qing Zheng. 2010-02-05. Pressure-induced unconventional superconductivity near a quantum critical point in CaFe2As2. https://doi.org/10.1088/0953-2048/23/5/054004

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