Fermi surface of CeTe

Article abstract of DOI:10.1016/S0304-8853(00)01132-X

CeTe is a typical Kondo lattice compound with antiferromagnetic ordering at 2 K. We have succeeded in observing the de Haas-van Alphen (dHvA) effect of CeTe. The dHvA frequencies denoted by a can be explained by the three equivalent ellipsoidal Fermi surfaces at the X points of the Brilluoin zone. We have discovered the splitting of the a branch into the α₁ and α₂ branches in most of the field directions, which is attributed to splitting of the up and down Fermi surfaces. The relatively large difference between the effective masses of α₁ is α₂ is observed for the field along the [111] direction.

Full text of DOI:10.1016/S0304-8853(00)01132-X

Journal of Magnetism and Magnetic Materials 226}230 (2001) 208}210
Fermi surface of CeTe
M. Nakayamaꢀꢀ*, T. Yamamizuꢀ, J. Kayaꢀ, N. Kimuraꢀ, H. Aokiꢀ, A. Ochiaiꢀ,
C. Terakuraꢁ, T. Terashimaꢁ, S. Ujiꢁ
ꢀCenter for Low Temperature Science, Tohoku University, Sendai 980-8578, Japan
ꢁNational Research Institute for Metals, Tsukuba, Ibaraki 305-0047, Japan
Abstract
CeTe is a typical Kondo lattice compound with antiferromagnetic ordering at 2 K. We have succeeded in observing the
de Haas}van Alphen (dHvA) e!ect of CeTe. The dHvA frequencies denoted by ꢀ can be explained by the three equivalent
ellipsoidal Fermi surfaces at the X points of the Brilluoin zone. We have discovered the splitting of the ꢀ branch into the
ꢀ and ꢀ branches in most of the "eld directions, which is attributed to splitting of the up and down Fermi surfaces. The
ꢁ
ꢂ
relatively large di!erence between the e!ective masses of ꢀ is ꢀ is observed for the "eld along the [1 1 1] direc-
ꢁ
ꢂ
tion. ꢀ 2001 Elsevier Science B.V. All rights reserved.
Keywords: Rare earth monochalcogenide; Fermi surface
Rare earth monochalcogenides have been the subject
of a number of studies for its simple NaCl-type cubic
structure and its attractive magnetic and transport prop-
erties. For example, SmS shows metal}insulator (M}I)
transition under a pressure of 6 kbar [1]. Tm monochal-
cogenides show continuous valence change under pres-
sure [2]. CeTe is a typical Kondo lattice compound and
shows attractive magnetic properties. The temperature
dependence of the electrical resistivity has the ln T range
which is the characteristic behavior of Kondo lattice
compounds [3]. The neutron di!raction and magnetic
susceptibility measurements show that type-II antifer-
romagnetic ordering occurs at 2 K with highly reduced
most e!ective experimental method to investigate the
electronic structure of metals. To observe the dHvA
e!ect, the sample must be of high quality. However, the
sample qualities of CeTe single crystals which were
grown in the past are not good enough to observe the
dHvA oscillations. In this paper, we present the "rst
observation of the dHvA e!ect among the rare earth
monochalcogenides.
The single crystal of CeTe was grown by the Bridge-
man method using a tungsten heater furnace. The start-
ing materials were the mixture of Ce (4N) and Te (6N)
and were sealed in an evacuated tungsten crucible. The
crucible was heated up to 20003C and grown at 2 mm/h.
The residual resistivity ratio is 18. This value shows that
the quality of the present single crystal is highest among
the crystals so far grown. The dHvA e!ect and AC
susceptibility were measured by the conventional "eld
modulation technique. A dilution refrigerator with a 20 T
superconducting magnet was used for the measurements.
Fig. 1 shows the magnetic "eld dependence of the
AC-susceptibility for the "eld along the [0 0 1] direction.
magnetic moment 0.3 ꢀ /Ce [4]. These attractive mag-
netic properties of the rare earth monochalcogenides
have the origin in its electronic structure, especially the
interaction between the 4f electrons and conduction d-
band [5}7]. However, the electronic structures of the rare
earth monochalcogenide have not been clari"ed yet. The
de Haas}van Alphen (dHvA) e!ect measurement is the
We have observed at least two anomalies at H "7.7 T
ꢂꢁ
and H "15.7 T but the origin of these anomalies is not
ꢂꢂ
clari"ed yet. The oscillations below 2 T may be attributed
*Corresponding author. Fax: #81-22-217-6484.
E-mail address: nakayama@mail.cc.tohoku.ac.jp
(M. Nakayama).
to the #ux jump of the superconducting magnet. The
dHvA e!ect measurements were performed above H
.
ꢂꢂ
0304-8853/01/$- see front matter ꢀ 2001 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 8 8 5 3 (0 0 ) 0 1 1 3 2 - X

M. Nakayama et al. / Journal of Magnetism and Magnetic Materials 226}230 (2001) 208}210
209
Fig. 1. Magnetic "eld dependence of the AC susceptibility for
the "eld along the [0 0 1] direction.
Fig. 3. Angular dependence of the dHvA frequencies of CeTe.
The open circles are the measured results and the solid lines are
guides to the eye.
Fig. 4. First Brillouin zone of CeTe.
Fig. 2. (a) dHvA oscillation and (b)its fast fourier transform
(FFT) spectrum of CeTe for the "eld along the [0 0 1] direction.
explained by three equivalent ellipsoidal Fermi surfaces
at the X point in the Brillouin zone. However, from this
simple model the dHvA frequency branches above 9000
and 10 000 T are expected to be around the [0 0 1] and
[1 1 0] directions, respectively. The disappearance of
these branches indicates that three ellipsoidal Fermi sur-
faces are possibly connected to each other at the ꢁ point.
Fig. 2 (a) and (b) shows the dHvA oscillations and its
fast fourier transform (FFT) spectrum for the "eld along
the [0 0 1] direction. Five dHvA frequencies have been
observed for this direction and they are denoted by ꢀ, ꢁ, ꢂ,
ꢃ and ꢀ. Fig. 3 shows the angular dependence of the
dHvA frequencies of CeTe. Nine dHvA branches have
been observed and they are denoted by ꢀ, ꢁ, ꢂ, ꢃ, ꢀ, ꢄ,
ꢅ and ꢆ. The ꢇ, ꢃ and ꢀ branches have approximately #at
angular dependences which indicate that these frequen-
cies arise from spherical Fermi surfaces. The ꢁ and
ꢂ branches are observed around the [0 0 1] direction and
the ꢄ, ꢅ and ꢆ branches are observed around the [1 1 0]
direction. The ꢀ branch is observed for almost all the "eld
directions and has the characteristic angular dependence.
Fig. 4 shows the "rst Brillouin zone of CeTe. The charac-
teristic angular dependence of the ꢀ branch can be mostly
It is noted that the ꢀ branch splits into the ꢀ and
ꢁ
ꢀ branches in most of the "eld directions. The measured
ꢂ
e!ective masses of ꢀ and ꢀ branches for the "eld along
ꢁ
ꢂ
the [1 1 1] direction are 5.6m and 12m , respectively.
ꢃ
ꢃ
We think that the splitting may be attributed to the
splitting of the up and down Fermi surfaces due to the
exchange interaction with the localized f electrons. The
large di!erence of the e!ective masses indicates that the
interaction between the f and conduction electrons is
more signi"cant for the one of the up and down Fermi
surface. It is not clear that which branch arises
from the up or down Fermi surface in this experiment.

210
M. Nakayama et al. / Journal of Magnetism and Magnetic Materials 226}230 (2001) 208}210
The band structure calculation is helpful to gain a better
understanding of the electronic structure of CeTe.
[3] J. Schoenes, F. Hulliger, J. Magn. Magn. Mater. 63}64
(1987) 43.
[4] D. Ravot et al., J. Phys. 41 (1980) 1117.
[5] B. Batlogg, E. Kaldies, A. Schlegel, P. Wachter: Phys. Rev.
B 14 (1976) 5503.
References
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