| Автор | Piqué, C |
| Автор | Blanco, J A |
| Автор | Burriel, R |
| Автор | Abad, E |
| Автор | Fernández-Rodríguez, J |
| Автор | Artigas, M |
| Дата выпуска | 2008-08-27 |
| dc.description | Using adiabatic calorimetry the heat capacity of a series of RFe<sub>x</sub>Mn<sub>12−x</sub> (R = Gd, Tb and Dy) compounds has been measured from 3 to 350 K. The substitution of Fe for Mn in RFe<sub>x</sub>Mn<sub>12−x</sub> influences both the magnetic interactions on the 3d sublattice and the magnetism of R (the Néel temperature doubles on going from x = 0 to 6 and the compounds become ferromagnetic for x = 8 with Curie temperatures of around 300 K). In pure TbMn<sub>12</sub> the heat-capacity data shows a λ-type anomaly associated with the independent cooperative magnetic ordering of the R sublattice (∼5 K), while the anomaly related to the Mn magnetic ordering (∼100 K) is rather smooth, as observed in other itinerant magnetic systems such as YMn<sub>12</sub>. In contrast, the substitution of Fe for Mn leads, on the one hand, to a more localized magnetic behaviour of the 3d sublattice, and, on the other, to magnetic polarization effects between the 3d and 4f sublattices, together with the disappearance of the cooperative magnetic ordering of the R sublattice due to the breaking of the antiferromagnetic symmetry in the 3d sublattice. This is reflected in the heat-capacity curve through a smooth Schottky-like anomaly. In the case of Gd compounds the magnitude of the exchange molecular-field parameter has been deduced by fitting the magnetic contribution to the heat capacity within a simple mean-field model. From this analysis we found that this molecular field acting on the rare-earth site increases with the iron concentration, reaching values as large as 48 T for the concentration x = 6. A similar analysis of the heat capacity in the ordered phase on the Tb compounds also leads to an enhancement of the molecular field with increasing Fe content. These results allow checking the possible crystal-field parameters for these RFe<sub>x</sub>Mn<sub>12−x</sub> compounds. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Копирайт | IOP Publishing Ltd |
| Название | Heat capacity of RFe<sub>x</sub>Mn<sub>12−x</sub> (R = Gd, Tb and Dy) compounds: wiping out a cooperative 4f–4f exchange interaction by breaking the 3d–4f magnetic symmetry |
| Тип | paper |
| DOI | 10.1088/0953-8984/20/34/345203 |
| Electronic ISSN | 1361-648X |
| Print ISSN | 0953-8984 |
| Журнал | Journal of Physics: Condensed Matter |
| Том | 20 |
| Первая страница | 345203 |
| Последняя страница | 345211 |
| Аффилиация | Piqué, C; Departamento de Física, Universidad de Oviedo, Campus de Viesques, E-33204 Gijón, Spain |
| Аффилиация | Blanco, J A; Departamento de Física, Universidad de Oviedo, Campus de Viesques, E-33204 Gijón, Spain |
| Аффилиация | Burriel, R; Instituto de Ciencia de Materiales de Aragón (CSIC–Universidad de Zaragoza), E-50009 Zaragoza, Spain |
| Аффилиация | Abad, E; Departamento de Física, Universidad de Oviedo, Campus de Viesques, E-33204 Gijón, Spain |
| Аффилиация | Fernández-Rodríguez, J; European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex, France |
| Аффилиация | Artigas, M; Instituto de Ciencia de Materiales de Aragón (CSIC–Universidad de Zaragoza), E-50009 Zaragoza, Spain |
| Выпуск | 34 |
