MAGNETIC SUSCEPTIBILITY OF (La1-xCax)2
CuO4-y (0 ≤ x ≤ 0.05)
K. Kojima, K. Ohbayashi, M. Udagawa, T. Hihara
To cite this version:
K. Kojima, K. Ohbayashi, M. Udagawa, T. Hihara. MAGNETIC SUSCEPTIBILITY OF
(La1-xCax)2 CuO4-y (0 ≤ x ≤ 0.05). Journal de Physique Colloques, 1988, 49 (C8), pp.C82199-C8-2200. <10.1051/jphyscol:19888987>. <jpa-00229277>
HAL Id: jpa-00229277
https://hal.archives-ouvertes.fr/jpa-00229277
Submitted on 1 Jan 1988
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JOURNAL DE PHYSIQUE
Colloque C8, Suppl6ment au no 12, Tome 49, dkcembre 1988
MAGNETIC SUSCEPTIBILITY OF (Lal-xCaz)2 C U O ~ (0
- ~
5 x 5 0.05)
K. Kojima, K. Ohbayashi, M. Udagawa and T . Hihara
Faculty of Integrated Arts and Sciences, Hiroshima University, Hiroshima 730, Japan
<
with X 0.05 X were measured as a function of temAbstract. - Magnetic susceptibilities ~f(La~-,Ca,)~
Cu04-,
perature. The oxides are antiferromagnetic for a: < 0.01 and superconductive for X 2 0.035. For 0.01 5 X 5 0.025 X is
decomposed of a Curie-Weiss and a linear temperature dependent components. The latter is of the same nature as in the
normal state of superconductive oxides.
The mechanism of the magnetic properties in the
high temperature superconductors containing Cu ion
is considered to be closely related t o that of the superconductivity. In (Lal-,Bax)2 CUO~-,for example,
the sample of X = 0 is an antiferromagnet with the
NBel temperature of T ~ = 2 2 0K [l]. With increasing
X, TN decreases rapidly, and for X 2 0.05 this system
becomes superconductive [2]. For 0.008 X 5 0.025
a glass-like magnetic state was suggested by the 1 3 ' ~ a
NQR measurement [3].
In this work the magnetic susceptibilities of
(Lal-,Ca,), CuOl-, with 0
X 5 0.05. were measured in order to investigate the X dependence of TN
and magnetic properties of the normal state of superconductive samples and the glass-like magnetic state at
lower X values. The procedure of the sample preparation was described elsewhere [4]. The magnetic susceptibility measurements were made from 4.7 K t o room
temperature by using a Faraday balance.
The temperature dependences of the susceptibility
X (T) are shown in figure 1. -The behaviours of X (T)
are classified into three concentration ranges: (a) 0
X 5 0.009, (b) 0.01
X 5 0.025 and (c) 0.035 5 X 5
0.05.
In the range (a) the X (T) curves for X = 0 and 0.009
show a broad peak at 268 and 8 K, respectively, which
is attributed to the antiferromagnetic(AF) transition.
The X (T) curves for X = 0.007 and 0.008 show no
clear peak, but an inflection (indicated by the arrows in
figure la) at about 150 K, which probably corresponds
to TN.TNdecreases rapidly from about 270 K for X = 0
to 8 K for 0.009 with increasing X, and it was reported
that TN is below 5 K for X = 0.01 [2]. Below about
40 K X (T) for X = 0, 0.007 and 0.008 show a small
decrease, which is attributed to the superconducting
transition as in pure LazCuO4 [5].
In the range (b) (Fig. lb) the susceptibilities increase monotonically with lowering the temperature,
showing no A F and superconducting transition.
In the range (c) (Fig. lc) the samples are superconductive below about 30 K. The susceptibilities at a
low field of 120 Oe, which are shown in the insert of
figure lc, suggest that the samples are bulk supercon-
<
<
<
<
Fig. 1. - Temperature dependence of magnetic susceptibility of (Lal-,Ca,)2 CuOr-, with 0 5 X 5 0.05 at 4.7 kOe.
The arrows indicates the antiferromagnetic transition temperature. In the insert the susceptibilities at 120 Oe are
shown, and the arrows indicate the superconducting transition temperatures.
ductors. The transition temperatures are 19 and 21 K
for z = 0.035 and 0.05, respectively. In the normal
state above about 30 K, the X (T) curves show almost
linear increases with increasing the temperature.
The rapid increase of X (T) at low temperatures in
the range (b) suggests a Curie-Weiss contribution of
C/ ( T - B), where C is the Curie constant and 0 the
paramagnetic Curie temperature. The Curie-Weiss fitting to the experimental data on X (T) , however, is unsuccessful. In the analysis of X (T) we assume a form
of X = C / (T - B) X O AT, where C, 0, X0 and A
are the fitting parameters. The experimental results
of X (T) for X = 0.015 and 0.025 are well described by
this equation, although the fitting to the experimental
U ~ . fitted curves are
data for X = 0.01 is U ~ S U C C ~ S S ~The
+ +
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19888987
C8 - 2200
JOURNAL DE PHYSIQUE
compared with the measured values in figure 2, where
the susceptibility values after substracting the CurieWeiss components are also plotted. The obtained parameters are listed in table I, where the effective Cu
moments pee,in stead of C, are given. The value of
pee for X = 0.015 is larger than that for X = 0.025.
This is consistent with the NQR result that the internal magnetic field at 13'~adecreases with increasing
X for 0.008 5 X 5 0.025 [3]. It is to be noted that
both the calculated curves for X = 0.015 and 0.025
exhibit systematic upward-deviations from the experimental data below about 10 and 7 K, respectively.
This seems to suggest some kind of ordering below
these temperatures, and we suppose that the deviations are associated with a glass-like magnetic state
previously referred [3, 61, although the temperature
range of measurements is limited to establish the definite conclusion:
Fig. 2. - Temperature dependence of magnetic susceptibility of (Lal-,Ca,)2 Cu04-, with X = 0.015 and 0.025. The
open circles indicate the measured values, and the curves
represent the fitting ones of X = C/(T - 8 ) + X 0 + A T with
the parameters listed in table I. The closed circles indicate the components of susceptibility after subtracting the
Curie-Weiss components.
Table I.
(Lal-,C&),
- Magnetic susceptibility data for
CUO~-~
The susceptibilities in the range (b) exhibit a linear
temperature dependent contribution, which probably
come from the same origin as those of X (T) in the normal state of the superconducting samples of the range
(c). The linear temperature dependence of X (Tjwas
observed in (Lal-,Sr,), CUO~-,and is attributed to
delocalized electron contributions [7]. This suggests
the presence of delocalized electrons in the samples of
the range (b), which are semiconductive at low temperatures [4]. It is supposed that the delocalized electrons in the range (b) have a rather low mobility, and,
with increasing X, the delocalized electron states overlap with each other, resulting in the superconducting
state in the range (c).
In conclusion, (Lal-,Ca,), CuO4-, are antiferromagnetic for X < 0.01 and superconductive for X 1
0.035. In the intermediate range of X the susceptibility can be decomposed of a Curie-Weiss component
and a linear temperature dependent one (including a
constant). The latter is of the same nature as the
susceptibility in the normal state of superconductive
oxides. The magnetic property of this system varies
continuously with increasing X.
[l] Vaknin, D., Shinha, S. K., Moncton, D. E., Johnston, D. C., Newsam, J. M., Safinya, C. R. and
King, H. E., Jr., Phys. Rev. Lett. 58 (1987) 2802.
[2] Fujita, T., Aoki, Y., Maeno, Y., Sakurai, J.,
Fukuba, H. and Fujii, H., Jpn J. Appl. Phys. 26
(1987) L368.
[3] Kitaoka, Y., Ishida, K., Hiramatsu, S. and
Asayarna, K., J. Phys. Soc. Jpn 57 (1988) 734.
[4] Kojima, K., Ohbayashi, K., Udagawa, M. and Hihara, T., Jpn J. Appl. Phys. 27 (1988) L852.
[5] Grant, P. M., Parkin, S. S. P., Lee, V. Y., Engler,
E. M., Ramirez, M. L., Vazquez, J. E., Lim, G.,
Jacowitz, R. D. and Greene, R. L., Phys. Rev.
Lett. 58 (1987) 2482.
[6] Budnick, J. I., Chamberland, B., Yang, D. P., Niedermayer, Ch., Golnik, A., Recknagel, E., Rossrnanith, M. and Weidinger, A., Ewophys. Lett. 5
(1988) 651.
[7] Allegier, C., Schilling, J. S., Ku, H. C., Kalvius,
P. and Shelton, R. N., Solid State Commun. 64
(1987) 227.