X.P. Zhong

Magnetic and crystallographic characteristics of rare-earth ternary carbides derived from R2Fe17 compounds

Abstract We have studied the magnetic properties of the rhombohedral R 2 Fe 17 C compounds with R = Ce, Pr, Sm, Gd, Tb, Dy, Ho or Y and the hexagonal R 2 Fe 17 C compounds with R = Er, Tm or Lu. For all compounds the lattice parameters were determined. The Curie temperatures were found to be considerably enhanced with respect to the C-free counterparts. The magnetic anisotropy of the R 2 Fe 17 C compounds was studied on magnetically aligned powders in field strengths up to 35 T. The rare-earth sublattice anisotropy is much stronger in R 2 Fe 17 C than in R 2 Fe 17 , leading to an easy c -axis anisotropy in Sm 2 Fe 17 C even at room temperature. The Curie temperatures and the high field data obtained at 4.2 K were analysed in terms of a mean field model.

Magnetic coupling in the tetragonal rare earth iron compounds of the type R(Fe,V)12

Abstract The temperature dependence and the field dependence (up to 35 T) at 4.2 K of the magnetization of several compounds of the type RFe12−xVx, were studied. The magnetic isotherms at 4.2 K as well as the temperature dependence of the magnetization were analysed with a mean field model. The magnetic coupling constant JRT between the moments of the rare earth (R) and 3d (T) element in the Hamiltonian H = −ΣT2JRTSR·ST derived from both types of measurements was found to differ considerably. Our results suggest that a mean field model does not lead to a consistent description of all of the magnetic properties if the presence of a magnetic moment on the vanadium atoms is not taken into account.

Magnetic coupling in CaCu5‐type rare‐earth cobalt compounds

The composition of rare‐earth cobalt compounds of the hexagonal CaCu5‐structure type varies from RCo5 to approximately RCo6 when passing through the lanthanide series. We have studied the field dependence (up to 35 T) at 4.2 K of the magnetization of several compounds of this series, including various pseudobinary compounds of the type R1−xYxCo5+δ and GdCo5−rNir. The magnetic isotherms at 4.2 K were analyzed with a mean‐field model. The magnetic coupling constant JRT between the moments of the rare‐earth (R) and 3d (T) element in the Hamiltonian H = −Σ2JRTSR⋅ST derived from these measurements was found to have a tendency to decrease with increasing atomic number of the lanthanide involved.

Magnetic coupling in rare-earth compounds of the type R2Ni17

Abstract The temperature dependence and the field dependence (up to 35 T) at 4.2K of the magnetization of several compounds of the type R2−xYxNi17 were studied. The magnetic isotherms at 4.2 K were analyzed with a mean-field model. The magnetic coupling constant JRNi between the moments of the rare-earth (R) and Ni element in the Hamiltonian H = −ΣNi2JRNiSR SNi were compared with the coupling constants derived from a mean-field analysis of the temperature dependence of the magnetization of the R2Ni17 compounds. From a comparison of the magnetic coupling constants found by means of high-field measurements of R2T17 compounds with T∼Ni, Co, Fe it follows that the RT coupling in the Ni compounds is much lower than in the corresponding Co and Fe compounds.

Study of magnetic interactions in ferrimagnetic systems in the Amsterdam high-field installation

Abstract Magnetizations of fine-powder samples of R 2 Co 14 B-type compounds have been measured in the Amsterdam High-Field Installation in fields up to 35 T at 4.2 K. The effect of the field-induced non-collinearity of the 3d and 4f sublattice magnetizations is clearly manifested at high fields and the magnetization process is analyzed within a two-sublattices model. The exchange field acting on the R spin moment varies from 175 T in Gd 2 Co 14 B to 150 T in Ho 1.8 La 0.2 Co 14 B.

High-field study of R2Fe17C compounds

Abstract Magnetically-aligned samples of ferrimagnetic compounds of the R 2 Fe 17 C series with the heavy rare earths Gd, Tb, Dy, Ho, Er and Tm have been studied at 4.2 K in magnetic fields up to 35 T. The exchange field of 225 T and the spin-exchange coupling J Dy-Fe / k = -7.2 K have been derived for Dy 2 Fe 17 C and full magnetization curves have been calculated.

Magnetic coupling in rare earth iron compounds of the type RFe4B

We have studied the temperature dependence of the magnetization and its field-dependence (up to 35 T) at 4.2 K in several series of compounds of the type R1-xLuxFe4B (R = Ho, Er, Tm). The magnetic isotherms at 4.2 K as well as the temperature dependence of the magnetization were analysed with a mean field model. The magnetic coupling constant JRFe in the Hamiltonian H = - ΣFe 2JRFeSR · SFe was found from both types of measurements to be equivalent to about -10.5 K.

Field‐induced transitions in Ho2Co17 studied in fields up to 50 T

High‐field magnetization studies have been performed at 4.2 K on single‐crystalline Ho2Co17 in the high‐field facilities of the Universities of Amsterdam and Osaka up to magnetic fields of 38 and 50 T, respectively. Several magnetic transitions have been observed for field directions in the easy hexagonal plane in the field range between 20 and 50 T. The transitions reflect field‐induced changes in the configuration of the holmium and cobalt magnetic moments and are a measure for the intersublattice‐coupling parameter.

Field-induced transitions in Ho sub 2 Co sub 17 studied in fields up to 50 T

High‐field magnetization studies have been performed at 4.2 K on single‐crystalline Ho2Co17 in the high‐field facilities of the Universities of Amsterdam and Osaka up to magnetic fields of 38 and 50 T, respectively. Several magnetic transitions have been observed for field directions in the easy hexagonal plane in the field range between 20 and 50 T. The transitions reflect field‐induced changes in the configuration of the holmium and cobalt magnetic moments and are a measure for the intersublattice‐coupling parameter.

Magnetic coupling in rare-earth-cobalt compounds of the type R2Co7

Abstract We have studied the field dependence (up to 35 T) of the magnetization at 4.2 K of several compounds of the type (R, Y) 2 Co 7 (R = rare earth). The magnetic isotherms at 4.2 K were analysed with a mean-field model. The magnetic-coupling constant J RCo between the moments of the rare earth and Co in the Hamiltonian H = Σ R 2J RCo S R · S Co were determined and were found to be larger than the coupling constants in other intermetallics of rare earths and Co studied thus far.