HAL Id: jpa-00229275
https://hal.archives-ouvertes.fr/jpa-00229275
Submitted on 1 Jan 1988
HAL is a multi-disciplinary open access
archive for the deposit and dissemination of
sci-entific research documents, whether they are
pub-lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d’enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.
EFFECT OF IONIC SIZE ON MAGNETIC
ORDERING IN RBa2Cu3Oy CERAMICS
T. Kistenmacher
To cite this version:
JOURNAL DE PHYSIQUE
Colloque C8, Supplbment au no 12, Tome 49, dbcembre 1988
EFFECT OF IONIC SIZE ON MAGNETIC ORDERING IN RBa2Cu30y CERAMICS
T. J. Kistenmacher
Applied Physics Laboratory, The Johns Hophins University, Laurel, M D 20707, U.S.A
Abstract. - The effect of variations in the radius of the rare-earth ion R in RBa2Cu30y ceramics on the N6el temperature
(TN) and magnetic entropy are identified. Parallel trands in TN and the de Gennes factor with radius indicate that superexchange leads to antiferrornagnetism in the rare-earth sublattice.
Almost immediately following the discovery of 2 . 5
high-T, superconductivity in the YBa2Cu30, system
[l], it was shown that substitution for Y by a num- 2
ber of magnetic and nonmagnetic rare-earths (R) does
not dramatically affect the superconducting behavior 1 .S [2]. Subsequently, specific heat, calorimetric, suscepti- U Y bility, and Mossbauer studies [3] revealed anomalies z associated with magnetic ordering in the rare-earth 1
sublattice. The antiferromagnetic ordering of the cou-
pled moments and the two-dimensional (Er [4]) and . 5
three-dimensional (Dy [5] and Gd [6]) magnetic struc-
ture have been confirmed and elucidated by neutron o
scattering. .
-
The nature of the interaction mechanism between rare-earth moments has, however, remained a mat- ter for speculation. The near Scaling of the observed NBel temperature (TN) with the de Gennes factor,
( g j
-
J (J+
l ) , for TN>
0.6 K has led to the sug-gestion that antiferromagnetic ordering is dominated by spin-spin exchange interactions via the conduction
electrons (RKKY coupling). However, since the mag- netism is apparently independent of the conductiv- ity in orthorhombic (near stoichiometric, supercon- ducting) and tetragonal (oxygen-deficient, insulating) GdBa2Cus 0, [3], dipolar and superexchange mecha- nisms have also been considered.
A factor that has not received detailed consideration in previous reports is that the variation in ionic radius (RI) for the rare-earth ion produces sizable and sys- tematic modifications in crystalline structure [7, 81. It seemed then of interst to investigate the trend in NBel temperature and magnetic entropy with the radius [g] of the rare-earth ion in the RBa2Cu30y ceramics. Pic- tured in figure 1A is the variation in TN with RI, including that for the parent compound YBa2Cu30, - where TN was taken to be 0 K. Interpretation of this unusual visualization is facilitated by comparison with the variation of the de Gennes factor with RI, see figure 1B. The strong correspondence between fig- ures 1A and 1B suggests that the subtle, but signif- icant, changes in crystal parameters with RI [B] are indeed reflected in the coupling mechanism responsi- ble for the magnitude of TN.
Similar considerations apply to systematic trends
0
1.05 Y 1.09 1 . 1 3 1 . 1 7
I O N I C RRDIUS (E)
Fig. 1. - (A) TN versus the ionic radius of the rare-earth
ion; (B) de Gennes factor versus ionic radius.
in the low-temperature magnetic entropy of the RBaaCu30, ceramics. With results taken from L'ee, et al. [3], plots of the variation in S (TN) /TN and S (To) /To (TO 2: 0.5 K) with RI are presented in figure
2. Clearly, the trend in S (TN) /TN with RI parallels that exhibited by TN itself. More interesting is the trend exhibited by S (To) /To, with the magnetic en- tropy falling expectedly and systematically with de- creasing radius (decreasing cell volume) for the Nd through Dy ceramics. The anomalously high values of S (TN) /TN and S (To) /To for the Er compound can be traced to the excess entropy associated with the ab- sence of three-dimensional ordering of moments in this ceramic.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19888985
C8 - 2196 JOURNAL DE PHYSIQUE
DY
0
1.05 1.03 1.13 1.17 IONIC RRDIUS
Fig. 2. - (A) Variation of S ( T N ) ITN with ionic radius; (B) Variation of S (To) /To with ionic radius.
In summary, the effects of the variation in crystal parameters with the ionic radius of the rare-earth ion in RBa2Cu30, ceramics on the NBel temperature and magnetic entropy are clearly evident. In particular, the parallel trends in TN and the de Gennes factor with ionic radius (coupled with the invariance of
TN
with conductivity) seem t o strongly support superexchange as the dominant term leading t o antiferromagnetic or- dering of the rare-earth sublattice in RBaaCuaO, ce- ramics.Acknowledgement
Support by the Department of the Navy under con- tract N00039-874-5301 is acknowledged.
[l] Wu, M. K., Ashburn, J. R., Torng, C. J., Hor, P. H., Meng, R. L., Gao, L., Huang, Z. J., Wang, Y. Q. and Chu, C. W., Phys. Rev. Lett. 58 (1987) 908.
[2] See, for example, Hor, P. H., Meng, R. L., Wang, X. Q., Gao, L., Huang, Z. J., Bechtold, J., Forster, K. and Chu, C. W., Phys. Rev. Lett. 58 (1987) 1891.
[3] Willis, J. O., Fisk, Z., Thompson, J . D., Cheong, S.-W., Aikin, R. M., Smith, J . L. and Zirngiebl,
E., J. Magn. Magn. Mater. 67 (1987) L139; Brown, S. E., Thompson, J. D., Willis, J. O.,
Aikin, R. M., Zirngiebl, E., Smith, J. L., Fisk, Z. and Schwarz, R. B., Phys. Rev. B 36 (1987) 2298;
Ho, J. C., Hor, P. H., Meng, R. L., Chu, C. W. and Huang, C. Y., Solid State Commun. 63 (1987) 711;
Dunlap, B. D., Slaski, M., Hinks, D. G., Soder- holm, L., Beno, L., Zhang, K., Segre, C. U., Crab- tree, G. W., Kwok, W. K., Malik, S. K., Schuller, I. K., Jorgensen, J. D. and Sungaila, Z., J. Magn.
Magn. Mater. 68 (1987) L139;
Nakamura, F., Tominaga, A. and Narahara, Y.,
Jpn J. Appl. Phys. 26 (1987) L1734;
Reeves, M. E., Citrin, D. S., Pazol, B. G., Fied- mann, T. A. and Ginsberg, D. M., Phys. Rev. B
36 (1987) 6915;
Ramirez, A. P,, Schneemeyer, L. F. and Waszczak, J. V., Phys. Rev. B 36 (1987) 7145; Alp, E. E., Soderholm, L., Shenoy, G. K., Hinks, D. G., Capone, D. W., Zhang, K. and Dunlap, B. D., Phys. Rev. B 36 (1987) 8910;
Dunlap, B. D., Slaski, M., Sungaila, Z., Hinks, D. G., Zhang, K., Segre, C., Malik, S. K. and Alp, E. E., Phys. Rev. B 37 (1988) 592;
Ferreira, J . M., Lee, B. W., Dalichaouch, Y., Torikachvili, M. S., Yang, K. N. and Maple, M. B.,
Phys. Rev. B 37 (1988) 1580;
Lee, B. W., Ferreira, J. M., Dalichaouch, Y., Torikachvili, M. S., Yang, K. N. and Maple, M. B.,
Phys. Rev. B 37 (1988) 2368.
[4] Lynn, J. W., Li, W.-H., Li, Q., Ku, H. C., Yang, H. D. and Shelton, R. N., Phys. Rev. B 36 (1987) 2374.
[5] Goldman, A. I., Yang, B. X., Tranquada, J., Crow, J. E. and Jee, C.-S., Phys. Rev. B 36
(1987) 7234.
[6] McK. Paul, D., Mook, H. A., Hewat, A. W., Sales, B. C., Boatner, L. A., Thompson, J. R.
and Mostoller, M., Phys. Rev. B 37 (1988) 2341. [7] Tarascon, J. M., McKinnon, W. R., Greene, L. H.,
Hull, G . W. and Vogel, E. M., Phys. Rev. B 36
(1987) 226.
[8] Kistenmacher, T. J., Solid State Commun. 65
(1988) 981.
