Magnetic, thermodynamic, and electrical transport properties of ternary equiatomic ytterbium
compounds YbTM „ T transition metal, M Sn and Bi…
D. Kaczorowski*
W. Trzebiatowski Institute for Low Temperature and Structure Research, Polish Academy of Sciences,
P.O. Box 1410, 50-950 Wroclaw 2, Poland
A. Leithe-Jasper, P. Rogl, and H. Flandorfer
Institut fu ¨r Physikalische Chemie der Universita ¨t Wien, Wa ¨hringerstrasse 42, A-1090 Vienna, Austria
T. Cichorek
W. Trzebiatowski Institute for Low Temperature and Structure Research, Polish Academy of Sciences,
P.O. Box 1410, 50-950 Wroclaw 2, Poland
R. Pietri and B. Andraka
Department of Physics, University of Florida, P.O. Box 118440, Gainesville, Florida 32611
Received 21 April 1998; revised manuscript received 2 November 1998
Physical behavior of several YbTM intermetallics has been studied by means of x-ray powder diffraction,
magnetization, dc magnetic susceptibility, heat capacity, and electrical resistivity measurements. The com-
pounds YbT Bi with T =Cu, Ag, Au and YbT Sn with T =Ag, Au, Zn were shown to be nonmagnetic due to
the presence of divalent ytterbium ions. The bismuthide YbPdBi as well as the stannides YbRhSn and YbPtSn
were found to exhibit localized magnetism of almost trivalent Yb ions. The electrical behavior of these three
phases is characteristic of dense Kondo systems, and their low-temperature specific heat data indicate a
possible heavy fermion ground state. S0163-18299912525-6
I. INTRODUCTION
Ternary equiatomic phases of ytterbium YbTM , where T
stands for a d-electron transition metal and M is an element
from the IIIA, IVA or VA group of the Periodic Table, have
attracted in recent years a widespread attention, mainly due
to their highly unusual physical properties. Besides well-
known mixed valent systems, like YbCuAl Ref. 1 and
YbPdIn,
2
the YbTM series comprises antiferromagnetically
or ferromagnetically ordered Kondo lattices, e.g., YbPtGa
Ref. 3 and YbNiSn,
4
respectively. A great deal of interest
has been devoted to ytterbium-based heavy fermion systems,
such as antiferromagnetic YbNiAl Ref. 5 or paramagnetic
YbPdSb and YbPdBi.
6,7
The semimetallic bismuthide
YbPtBi Ref. 8 has deserved a special attention as that it
displays both a low-carrier conductivity and a huge low-
temperature Sommerfeld coefficient that exceeds 8 J/mol
K
2
.
9
In the present paper we focus on the synthesis, structural
chemistry and physical properties of several YbTM com-
pounds, where T is either a platinum group or copper group
element and M is either Sn or Bi. To the best of our knowl-
edge, the only bismuthide that has been characterized mag-
netically was YbPdBi.
6,7,10
In the course of the present study
a paper by Katoh et al. has appeared
11
that reported on a
similar independent investigation on the magnetic and elec-
trical behavior of the YbT Sn stannides with T =Ag, Pt, and
Au.
II. EXPERIMENTAL
Starting materials of 99.9% minimum purity were used in
the form of ingots Yb, Bi, Sn, Cu, Ag, Au, foils Pd or
powders Rh, Pt. Due to the high vapor pressure of ytter-
bium metal at elevated temperatures, synthesis of single-
phase material turned out to be quite cumbersome and was
achieved following two different routes. In order to benefit
from the advantages of a closed system, one method was to
enclose the starting materials in small cylindrical tantalum
cans, which were sealed by arc-welding under pure argon.
The samples, each with a total weight of about 0.5 g, were
melted and, in order to attain proper homogenization, re-
melted in an induction furnace under continuous shaking of
the crucible in a stream of high purity argon. The tantalum
crucibles were then sealed in quartz tubes under vacuum and
annealed at 600 °C for 7 days and finally quenched in water.
The samples synthesized by this method were found to be
melt homogeneously, covering large parts of the inner cru-
cible wall in the form of a thin layer, which was usually
crushed to smaller pieces when opening the crucible. Thus
samples prepared by this method proved unfit for any trans-
port measurements and were therefore mainly used for x-ray
phase analysis and magnetic measurements.
In order to produce samples of well defined shapes, con-
ventional arc-melting of 0.5 g samples under a protective
argon-gas atmosphere 99.999 mass% on a water cooled
copper hearth was applied as the second method of synthesis.
To achieve single-phase material usually several attempts
were undertaken starting from various stoichiometries to
PHYSICAL REVIEW B 1 JULY 1999-I VOLUME 60, NUMBER 1
PRB 60 0163-1829/99/601/42212/$15.00 422 ©1999 The American Physical Society