Y. Kawasaki et al., Exotic magnetic and superconducting phases in CeCU2Si2 close to magnetically ordered state: Cu-NQR study, J MAGN MAGN, 226, 2001, pp. 374-375
We report Cu-NQR results under pressure on heavy-fermion (HF) superconducto
r CeCu2Si2 close to a magnetic phase, Ce0.99Cu2.02Si2 and CeCu2(Si0.98Ge0.0
2)(2). It is found that an application of a minute pressure exceeding 0.3 G
Pa markedly suppresses low-energy magnetic fluctuations observed at ambient
pressure (P = 0) in Ce0.99CU2.02Si2, Correspondingly, anomalous supercondu
cting (SC) characteristics evolve into conventional HF-SC ones with increas
ing pressure. In the latter. the Ge substitution works as a negative chemic
al pressure. CeCu2(Si0.98Ge0.02)(2) reveals a magnetic phase transition at
T-N = 0.75 K followed by the SC phase transition at T-c similar to 0.4 K at
P = 0. It is suggested experimentally that the magnetic fluctuations seen
in Ce0.99Cu2.02Si2 at P = 0 possesses a quantum critical character of both
SC and magnetically ordered states. (C) 2001 Elsevier Science B.V. All righ
ts reserved.