Magnetic and electronic properties of ternary uranium antimonides UT Sb
2
„ T 3 d -, 4 d -, 5 d -electron transition metal…
D. Kaczorowski
*
W. Trzebiatowski Institute for Low Temperature and Structure Research, Polish Academy of Sciences,
P.O. Box 937, 50-950 Wroclaw 2, Poland
R. Kruk
†
and J. P. Sanchez
De ´partement de Recherche Fondamentale sur la Matiere Condense ´e, CEA/Grenoble, 17 rue des Martyrs,
38054 Grenoble Cedex 9, France
B. Malaman
Laboratoire de Chimie du Solide Mine ´ral associe ´ au CNRS (URA 158), Universite ´ Henri Poincare ´-Nancy I, B.P. 239,
54506 Vandoeuvre les Nancy Cedex, France
F. Wastin
European Commission, Joint Research Center, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany
Received 17 March 1998
Magnetic, electrical transport, neutron diffraction, and Mo ¨ssbauer measurements have been performed on a
series of uranium–transition-metal–antimonides UT Sb
2
( T =Fe, Co, Ni, Cu, Ru, Pd, Ag, and Au. Most of
these compounds were found to order magnetically at low temperatures and characterized as semimetallic
Kondo lattices with strongly screened magnetic moments. Combined neutron diffraction and Mo ¨ssbauer results
allowed determination of the magnetic structures adopted in antiferromagnetic UNiSb
2
, UPdSb
2
, and
URuSb
2
. The magnetic behavior found in UT Sb
2
phases is here discussed with a special emphasis on the role
of the f -p and f -d hybridization. S0163-18299800538-4
I. INTRODUCTION
Uranium compounds UTX
2
, where T is a 3 d -, 4 d -, or 5 d
transition metal and X stands for a pnictogen, form a numer-
ous family of ternaries, closely related to the well-known
UX
2
phases. Most of them crystallize in a simple tetragonal
structure space group P 4/nmm , see Fig. 1 usually referred
to in the literature as ZrCuSi
2
, HfCuSi
2
, UCuAs
2
, or
ZrCuSiAs type. Although UCuAs
2
was the first pnictide re-
ported to form with this structure,
1
the very first compound
for which the corresponding atomic positions have been de-
termined was HfCuSi
2
.
2
For this reason, accepting the argu-
ments presented recently by the authors of Ref. 3, the proto-
type name HfCuSi
2
will be consequently used in this and our
further papers on UTX
2
pnictides.
Previously, in a series of publications we reported on the
magnetic, transport, and thermal properties of several 1:1:2
uranium–transition-metal phosphides and arsenides Ref. 4,
and references cited therein. There, we addressed mainly the
problem of how the crystal-field potential acting on the ura-
nium atom and the exchange interactions between them are
modified when atoms of a given transition metal are embed-
ded into the unit cell of the respective UX
2
parent com-
pound. Moreover, particular attention was paid to the role of
the hybridization between the uranium 5 f states and the
transition-metal d -conduction states and the pnictogen
p -valence states in determining the behavior of these phases.
In the following we extend our discussion to the uranium
antimonides UT Sb
2
. We report here on the preparation of
several such compounds and present the results of bulk mag-
netic, electrical transport, neutron diffraction, and Mo
¨
ssbauer
investigations, performed on polycrystalline samples of these
materials.
II. EXPERIMENT
Polycrystalline samples of UT Sb
2
were prepared by arc
melting the constituent elements in a purified argon atmo-
FIG. 1. Crystal structure of UT Sb
2
compounds. The near-
neighbor environment of the Sb1 and Sb2 atoms is outlined.
PHYSICAL REVIEW B 1 OCTOBER 1998-II VOLUME 58, NUMBER 14
PRB 58 0163-1829/98/5814/922711/$15.00 9227 © 1998 The American Physical Society