NQR study of pressure induced superconductivity in CeCu₂Si₂

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 n Q of 63 Cu nuclei was observed below 3 GPa. However, 63 n 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.

Single Crystal Growth of the CeCu2Si2 Intermetallic Compound by a Vertical Floating Zone Method

“…This implies that the preparation path and parameters of CeCu 2 Si 2 crystals also have a great impact upon the physical behavior. So far, the crystal preparation, magnetism, and superconductivity of CeCu 2 Si 2 have been the most important subjects in the field of heavy fermion superconductors and still attract much attention. − …”

“…So far, the crystal preparation, magnetism, and superconductivity of CeCu 2 Si 2 have been the most important subjects in the field of heavy fermion superconductors and still attract much attention. [8][9][10] The preparation of CeCu 2 Si 2 single crystals with welldefined composition has contributed much to understanding the exotic behavior of this compound. Crystal growth attempts have been accomplished with various methods.…”