Magnetic phase diagram of FeCl 2 ⋅ 2 H 2 O
1988; American Physical Society; Volume: 37; Issue: 10 Linguagem: Inglês
10.1103/physrevb.37.5414
ISSN1095-3795
Autores Tópico(s)Thermal and Kinetic Analysis
Resumo${\mathrm{FeCl}}_{2}$\ensuremath{\cdot}${2\mathrm{H}}_{2}$O represents a metamagnet, which shows two jumps in the magnetization at temperatures below a critical endpoint (4.3 T; 11.2 K), if a magnetic field is applied along the easy direction \ensuremath{\alpha}. Below 11.2 K, with increasing field, an antiferromagnetic zero-field phase is followed by a ferrimagnetic and the paramagnetic saturated phase. By means of neutron diffraction in fields up to 6.4 T and magnetization experiments up to 15 T, magnetic phase diagrams were determined for applied fields out of the easy direction \ensuremath{\alpha} as well for the intermediate direction \ensuremath{\beta} and the hard direction \ensuremath{\gamma} as for the total \ensuremath{\alpha}-\ensuremath{\beta} plane. In particular, it should be emphasized that the ferrimagnetic phase does not disappear in this \ensuremath{\alpha}-\ensuremath{\beta} plane going from the direction \ensuremath{\alpha} to the direction \ensuremath{\beta}. Furthermore, an increasing N\'eel temperature has been observed for fields along the direction \ensuremath{\beta}. Calculations of the ${H}_{\ensuremath{\alpha}}$-${H}_{\ensuremath{\beta}}$ phase diagram at 0 K do not agree with the experiments, if well-known formulas for the exchange constants and the single-ion anisotropy are taken into account. If a simple assumption about the field dependence of one exchange constant is made, the agreement is excellent.
Referência(s)