P. Monachesi et A. Continenza, EFFECT OF COMPOSITION ON THE ANDERSON HYBRIDIZATION IN TERNARY CUBIC ALLOYS OF CE, Nuovo cimento della Societa italiana di fisica. D, Condensed matter,atomic, molecular and chemical physics, biophysics, 15(2-3), 1993, pp. 307-323
The cubic compounds of Ce with Zn, Ag and Cd are considered to behave
as Kondo lattices depending on applied pressure or alloying. In partic
ular their magnetic behaviour is ascribed to the possible competition
between the RKKY interaction and the Kondo effect. We calculate the hy
bridisation width DELTA of the Anderson model for the two ternary cubi
c compounds CeCd1-xAgx, CeCd1-xZnx. This quantity determines, along wi
th the position E(f) and correlation U of the Ce f-state, the antiferr
omagnetic coupling constant J(s-f) of the Kondo Hamiltonian. We start
from ab initio electronic calculations performed with the FLAPW method
in the LSDA and carry out an LCAO parametrisation of the band structu
re for the pure binary compounds. A virtual-crystal approximation is u
sed to obtain the LCAO parameters of the ternary alloys. We cheek the
accuracy of this approximation on CeCd0.5Zn0.5 by a self-consistent FL
APW calculation on the supercell Ce2CdZn, finding that it is satisfact
ory for the present purposes. We find that DELTA, in the whole concent
ration range, is affected quantitatively much more by substitution of
Cd by Ag than by Zn-isovalent to Cd-, although the latter one induces
a larger volume reduction. Moreover, the DELTA behaviour in CeCd1-xZnx
, contrasts with the expected volume dependence. This shows that elect
ronic effects may be more effective than electronic pressure alone (vo
lume effects) in determining the Kondo properties of substitutional sy
stems.