M. Elkholdi et al., MAGNETIC-PROPERTIES OF A LAYERED AND ANISOTROPIC RHOMBOHEDRAL COMPOUND - BI-2(1-X)GD2XTE3, Physical review. B, Condensed matter, 49(3), 1994, pp. 1711-1715
The paramagnetic resonance absorption spectra of Bi-2(1-x) Gd-2x Te-3
grown by the Bridgman technique have been measured at room temperature
. The magnetization measurements have been performed in magnetic-field
intensities up to 65 kOe at temperatures of 1.8, 4.2, 16, and 25 K. T
he EPR data show that the Gd3+ site has a C-3v symmetry, indicating a
true substitution of Bi3+ atoms by Gd3+. The curve fitting of the magn
etic-field dependence of the magnetization has been performed using a
Brillouin function representing isolated magnetic ions. An extra term
was introduced to represent the contribution of the pairs. The results
indicate a weak antiferromagnetic coupling between the Gd3+ ions. Thi
s is similar to the one found in the case of Pb-1-x Gd-x Te. The bond
lengths as well as the bond angles in the case of Bi-2((1-x)) Gd-2x Te
-3 and Pb-1-x Gd-x Te are compared. The similarity of the J(p)/k(B) va
lues (-0.5 K) in the two systems is explained in terms of superexchang
e interaction via anions between Gd3+.