https://doi.org/10.1140/epjb/e2004-00374-7
Electronic structure and magnetic properties of RMnX (R = Mg, Ca, Sr, Ba, Y; X = Si, Ge) studied by KKR method
1
Laboratoire de Chimie du Solide Minéral, Université
Henri Poincaré - Nancy I, Associé au CNRS (UMR 7555),
BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France
2
Faculty of Physics and Nuclear Techniques,
AGH University of Science and Technology, Al. Mickiewicza 30,
30-059 Kraków, Poland
Corresponding author: a Bernard.Malaman@lcsm.uhp-nancy.fr
Received:
20
April
2004
Published online:
14
December
2004
Electronic structure calculations, using the charge and
spin self-consistent
Korringa- Kohn-Rostoker (KKR) method, have been performed for several
RMnX compounds (R = Mg, Ca, Sr, Ba, Y; X = Si, Ge) of the CeFeSi-type
structure.
The origin of their magnetic properties has been investigated emphasizing
the role of the Mn sublattice. The significant influence of the Mn-Mn and
Mn-X interatomic distances on the Mn magnetic moment value is delineated
from our computations, supporting many neutron diffraction data.
We show that the marked change of with the Mn-Mn and Mn-X
distances resulted from a redistribution between spin-up and
spin-down d-Mn DOS rather than from different fillings of the Mn
3d-shell. The obtained KKR results are discussed considering
the Stoner-like and covalent magnetism effects.
From comparison of electronic structure of RMnX in different
magnetic states we conclude that the antiferromagnetic coupling in
the Mn (001) plane considerably increases the Mn magnetic moment with
respect to the ferromagnetic arrangement.
Bearing in mind that the neutron diffraction data reported for the RMnX
compounds are rather scattered, the KKR computations of
are in
fair agreement with the experimental values.
Comparing density of states near EF obtained in different
magnetic orderings, one can notice that the entitled RMnX systems
seem to `adapt' their magnetic structures to minimize the DOS in the
vicinity of the Fermi level. Noteworthy, the SrMnGe antiferromagnet
exhibits a pseudo-gap behaviour at EF, suggesting anomalous
electron transport properties.
In addition, the F-AF transition occurring in the disordered
La
YxMnSi alloy for the 0.8<x<1 range is well supported
by the DOS features of La0.2Y0.8MnSi.
This latter result sheds light on the magnetic structure of the YMnSi
compound.
In contrast to the investigated RMnX compounds, YFeSi was found to
be non-magnetic, which is in excellent agreement
with the experimental data.
PACS: 71.20.Lp – Electron density of states, intermetallic compounds / 75.50.Ee – Antiferromagnets
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004