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NQR study of pressure induced superconductivity in CeCu 2 Si 2
Author(s) -
Fujiwara K.,
Okazaki Y.,
Hata Y.,
Miyoshi K.,
Takeuchi J.,
Kobayashi T. C.,
Geibel C.,
Steglich F.
Publication year - 2010
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200983050
Subject(s) - nuclear quadrupole resonance , antiferromagnetism , superconductivity , condensed matter physics , valence (chemistry) , fermi level , density of states , quadrupole , materials science , chemistry , physics , atomic physics , nuclear physics , organic chemistry , electron
Abstract We have measured nuclear quadrupole resonance (NQR) for 63 Cu nuclei under high pressure up to 4.8 GPa. A linear increase in NQR frequency $^{63} \nu _{\rm Q}$ of 63 Cu nuclei was observed below 3 GPa. However, $^{63} \nu _{\rm Q}$ deviates gradually from the linear relation above 3.5 GPa. The downward deviation is associated with a change of valence and consistent with the results of band calculations with the structural parameters under pressure. Antiferromagnetic (AFM) spin fluctuations are drastically suppressed with increasing pressure, whereas T c increases from 0.7 K at ambient pressure to 1.64 K at 4.2 GPa. We have found that bulk superconductivity suddenly disappears at 4.8 GPa accompanied with a rapid decrease in the density of states at the Fermi level.These are indenter pressure cells for NQR measurements.