ISSN:
1089-7550
Quelle:
AIP Digital Archive
Thema:
Physik
Notizen:
In 1967, Holtzberg, Gambino, and McGuire [J. Phys. Chem. Solids 28, 2283 (1967)] observed that intermetallic Gd5Si4 exhibits TC = 336 K. This is remarkable in that the TC of Gd (∼291 K) is increased by chemical union with a nontransition metal, which is rare, if not unique. In the present study, magnetization-temperature behavior of Gd5Si4 and (Gd1−xMx)5Si4 systems with M=La or Y were studied and compared with the Brillouin function (BF) to see if molecular-field theory is obeyed. Demagnetization near TC is much sharper for the alloys than expected from the BF. As examples, at T/TC = 0.9, the BF for Gd5Si4 gives M/M0 = 0.38, whereas the observed values range from 0.99 [for (Gd0.8Y0.2)5Si4] to 0.5 [for (Gd0.6La0.4)5Si4]. The factors responsible for these strong deviations from the BF and the high-TC values of these alloys are as yet unclear. X-ray patterns for yttrium-doped samples with x=0.1–0.5 and La with x=0.05 and 0.1 appear identical to the pattern for Gd5Si4, indicating no structural change. For La substitution of x=0.2 and above, there is a change from orthorhombic to tetragonal structure. All of the compounds show a decrease in Curie temperature and magnetic moment as Gd is decreased, as expected because of the replacement of Gd by a nonmagnetic species.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.347953
