We have measured nuclear quadrupole resonance (NQR) for *Cu nuclei under high pressure up to 4.8 GPa.A linear increase in NQR frequency *νQ of *Cu nuclei was observed below 3 GPa. However, *νQ 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 Tc increases from 0.7K at ambient pressure to 1.64K 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.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics