EPR STUDY OF EXCHANGE INTERACTIONS IN THE NONMAGNETIC KONDO SYSTEM LA1-XCEXCU6

The EPR of paramagnetic impurities Gd3+ and Mn2+ was studied in nonmag netic Kondo system La1-xCexCu6 containing in the 1.6-200 K range. The exchange interaction parameters of gadolinium and manganese ions with conduction electrons, of cerium ions with conduction electrons and wit h one another, the Kondo temperature of cerium ions, and the temperatu re behavior of cerium-ion spin-fluctuation rate have been determined. A pseudogap in the density of states at the Fermi level has been detec ted in the CeCu6 regular system, which is apparently due to s-f hybrid ization. This pseudogap can be destroyed by introducing an aluminum im purity, which induces strong conduction-electron scattering. It was al so found that RKKY interaction among manganese ions in CeCu6-yMny is c onsiderably stronger than it is in LaCu6-yMny, which implies enhanceme nt of nonlocal spin susceptibility due to an f band contribution to co nduction-electron states. (C) 1998 American Institute of Physics.