Abstract
In order to investigate magnetic properties in the vicinity of the magnetic to superconducting (SC) phase boundary, we have performed Cu-NQR measurements under hydrostatic pressure (P) on two off-stoichiometric Ce1+xCu2+ySi2 polycrystals: Ce0.99Cu2.02Si2 (denoted as Ce 0.99) exhibits the anomalous ground state so-called A phase dominated by critical magnetic correlations and Ce0.975Cu2Si2 (Ce 0.975) shows a static magnetic ordering at ambient P. With increasing P which enhances the Kondo temperature, the fraction of the A phase becomes markedly suppressed, and the SC fraction increases correspondingly, although Tc stays nearly constant in the measured pressure range, P≤14.4 kbar. This shows that the P-induced transition from the A to the SC phases is of a first-order type, without passing through a quantum (T→0) phase transition. However, no superconductivity has been attained in Ce 0.975 up to 19.4 kbar. It is considered that the P-induced superconductivity is sensitive to the sample quality.
Similar content being viewed by others
References
D. Jaccard et al., Phys. Lett. A 163 (1992) 475.
F.M. Grosche et al., Phys. B 224 (1996) 50.
N.D. Mathur et al., Nature 394 (1998) 39.
G. Bruls et al., Phys. Rev. Lett. 72 (1994) 1754.
H. Nakamura et al., J. Phys. Condens. Matter 4 (1992) 473.
Y. Kitaoka et al., J. Phys. Soc. Japan 60 (1992) 2122.
K. Ishida et al., Phys. Rev. Lett. 82 (1999) 5353.
F. Steglich et al., J. Phys. Condens. Matter 8 (1996) 9909.
R. Modler et al., Phys. B 206/207 (1995) 586.
R. Feyerherm et al., Phys. B 206/207 (1995) 596; Phys. Rev. B 56 (1997) 699.
P. Gegenwart et al., Phys. Rev. Lett. 81 (1998) 1501.
Y. Kitaoka et al., Phys. B 206/207 (1995) 55.
F. Thomas et al., Phys. B 186-188 (1993) 303.
T. Moriya and T. Takimoto, J. Phys. Soc. Japan 60 (1992) 2122.
S. Ohsugi et al., J. Phys. Soc. Japan 60 (1996) 2351.
S. Nakamura et al., J. Phys. Soc. Japan 65 (1996) 4026.
O. Trovarelli et al., Phys. Rev. B 56 (1997) 678.
K. Ishida et al., in preparation.
S.C. Zhang, Science 275 (1997) 1089.