https://doi.org/10.1007/s100510050806
Quantum charge density fluctuations and the y-a phase transition in Ce*
1
Department of Physics, University of Antwerp, UIA,
2610 Antwerpen, Belgium
2
Institute of Physical
Chemistry of RAS, Leninskii prospect 31,
Moscow, 117915, Russia
Corresponding author: a alex@uia.ua.ac.be
Received:
19
October
1998
Published online: 15 June 1999
We have calculated the quantum quadrupolar interaction
due to charge density fluctuations of localized
4f-electrons in Ce by taking into account
the angular dependence, the degeneracy of the localized
4
orbitals and the spin-orbit coupling.
The calculated crystal field of 4f electronic states
is in good agreement with
neutron diffraction measurements.
We show that orientational ordering of quantum quadrupoles drives
a
phase transition
at
K which we assign with the
transformation.
In the
phase the centers of mass of the Ce atoms
still form a face centered cubic lattice.
The theory accounts for the first order character of the
transition and for the cubic lattice contraction which
accompanies the transition. The transition temperature
increases linearly with pressure.
Our approach does not involve Kondo spin fluctuations
as the significant process for the phase transition.
PACS: 71.10.-w – Theories and models of many electron systems / 71.27.+a – Strongly correlated electron systems; heavy fermions / 71.45.-d – Collective effects / 64.70.Kb – Solid-solid transitions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999