N. Tang

Magnetic properties of rare earth compounds of the type RCo11Ti

Abstract We have investigated the magnetic properties of rare earth compounds of the type RCo 11 Ti (R = Sm, Gd, Tb, Dy, Ho, Er, Tm and Y) by means of high-field and ac susceptibility measurements. From the experimental values of the saturation magnetisation at 4.2 K we have derived the magnitude of the Co moments in these compounds, which were found to be almost invariant across the series ( μ Co = 1.41 μ B ). We have determined the easy magnetisation direction in the various RCo 11 Ti compounds and found that the Co sublattice anisotropy favours an easy moment direction along the c -axis, whereas the rare earth sublattice anisotropy is governed by a positive second-order crystal field parameter ( A 2 0 > 0). Spin reorientation phenomena were observed for compounds with R = Dy, Er and Tm.

Magnetic properties of rare-earth compounds of the RCo10Mo2 type

acad sinica,inst met res,shenyang 110015,peoples r china. acad sinica,inst phys,beijing 100080,peoples r china.;zeng, dc (reprint author), univ amsterdam,van der waals zeeman lab,valckenierstr 65,1018 xe amsterdam,netherlands

Magnetic properties of LaFe13−xAlxNy compounds

Interstitial nitrides of the type LaFe13_xAl.~Ny have been synthesized and their magnetic properties have been investigated. It is found that the magnetic properties are drastically modified by the introduction of interstitial nitrogen. The physical origin of the changes is discussed. The magnetic properties of the LaFel3_xAlx compounds have been investigated by Palstra et al. [1,2], who found that this series displays complex magnetic behaviour. The magnetic properties vary dramatically with the concentration of aluminum. When the A1 concentration is higher than x = 5, the ferromagnetic state is instable with respect to the Fe-AI-Fe indirect exchange in the low-iron-concentration regime, leading to mictomagnetism. When the A1 concentration is lower than x = 1.8, the ferromagnetic state is destroyed by the direct antiferromagnetic exchange in the high-iron-concentration regime, leading to an antiferromagnetic state. We have synthesized the interstitial compounds LaFe13 xAlxNy [3] and investigated the effect of the interstitial nitrogen atoms on the magnetic properties of the compounds. Nitrogenation of the compounds was carried out by heating the powder of the compounds in the temperature range from 500 to 650°C, during 3 to 30 h, depending on the compound. The nitrogen contents were determined by weighing the mass gain after the nitrogenation. The introduction of nitrogen becomes more difficult with increasing AI concentration. More impurity c~-Fe was detected in the nitrides with higher x, whereas the X-ray diffraction patterns show that LaFell.sAll.sNz9 and LaFel0.sA12.sN2.7 are single phase. For x > 4.5, no nitrogen can be introduced. As a result of the decrease in nitrogen take-up with increasing AI concentration all compounds LaFe13_xAlxNy studied have approximately the same unit-cell volume. We investigated the temperature dependence of magnetization of both the parent and the nitrogenated compounds from 4.2 K to room temperature in a low static field (0.04 T). Fig. 1 shows the results. The curves for x = 1.5 in Fig. 1 show that the magnetism of LaFell.sAI1.5 has changed

High-field magnetization of U2T2X compounds (T = Co, Ni, Rh, Pd, Ir, Pt and X = In, Sn)

Abstract Structure parameters and magnetization in quasistatic fields up to 38 T at 4.2 K are reported for U2T2X compounds with T = Co, Rh, Ni, Pd, Ir, Pt and X = In, Sn, which crystalline in the tetragonal U3Si2 structure. Even the highest applied fields are not sufficient to achieve saturation of the magnetization in any of these compounds of which the majority is antiferromagnetic and some are Pauli paramagnets. The importance of 5f-ligand hybridization for the magnetism in these compounds is discussed.

Magnetic properties of ternary rare earth compounds of the type RCo10Ti2

Abstract The magnetic properties of rare-earth compounds of the type RCo 10 Ti 2 (R  Gd, Tb, Dy, Ho, Er and Y) were investigated by means of high-field measurements and AC-susceptibility measurements. From the experimental values of the saturation magnetisation at 4.2 K, we have derived the magnitude of the Co moments in these compounds, which were found to be almost invariant across the series ( μ Co = 0.95 μ B ). By contrast, high-field measurements made on compounds of the series YCo 12− x Ti x showed that the Co moment decreases very strongly with Ti concentration. A similar strong decrease is displayed by the corresponding Curie temperatures. We have determined the easy magnetisation direction in the various RCo 10 Ti 2 compounds and found that the Co-sublattice anisotropy favours an easy moment direction along the c -axis. The rare-earth-sublattice anisotropy is governed by a positive value of A 2 0 and seems to have increased relative to the Co-sublattice anisotropy compared to the situation in RCo 11 Ti.

Magnetic properties of RCo12-xTix compounds a novel series of ThMn12-type intermetallics

Abstract TMn 12 -type compounds of composition RCo 12− x Ti x have been prepared by arc melting and subsequent annealing. The magnetisation of various specimens has been measured both as a function of temperature as well as of applied fields up to 35 T. In YCo 12− x Ti x , both the Curie temperature and the Co-moments strongly depend on the Ti concentration. High-field free-powder magnetisation measurements show a substantial coupling between the R- and 3d-moments in case of R  Dy, Ho, Er. In ErCo 11 Ti and TmCo 11 Ti, spin reorientations are observed below 150 K.

Magnetic properties of DyCo10−xNixSi2 compounds

The temperature dependence of the magnetization of DyCo10−xNixSi2 compounds with x=0, 2, 4, and 6 was measured in fields up to 5.0 T and in the temperature range from 4.2 to 300 K in a SQUID magnetometer. Compensation temperatures were observed for the compounds with x=4 and 6. The values of the R‐T exchange interaction obtained by fitting the M‐T curves on the basis of two‐sublattice molecular‐field theory are compared with the values obtained from high‐field magnetization measurements on powder particles free to be oriented by the applied field. In all four compounds magnetic transitions are found in the ac‐susceptibility measurements which were carried out between 4.2 K and room temperature. The types of magnetic anisotropy were investigated by magnetization measurements on samples that were magnetically aligned at room temperature.

Magnetic properties of Er(Fe,Ni)10Si2 compounds

Abstract The magnetic properties of ErFe 10-x Ni x Si 2 compounds with x = 0,2,3,3.5,4,4.5 have been studied by measuring magnetization curves of free-powder samples at 4.2 K in fields up to 38 T and by measuring the temperature dependence of the AC susceptibility in the temperature range 4.2–300 K. In these compounds, the antiparallel alignment of the Er-and 3d-sublattice moments is broken in the applied fields and a bending process of the two sublattice magnetization is observed. An oscillatory behaviour of the magnetization is found which can be explained by taking into account the magnetic anisotropies of both the Er- and the 3d-sublattice up to K 4 . Below room temperature, a spin-reorientation is observed in all compounds. The spin-reorientation temperature increases with increasing Ni content.

Structure and magnetic properties of Er/sub 2/Fe/sub 17/C/sub x/ compounds

The interstitial carbides of Er/sub 2/Fe/sub 17/C/sub x/ with x=0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 have been synthesized by arc melting and by the Gas-Phase Interaction (GPI) method. The unit-cell volume of the compounds is found to increase with increasing carbon concentration. The dependence of Curie temperatures, spin-reorientation temperatures and the magnetic coupling on the carbon content has been investigated. The spin phase diagram of the series is given. >

The dysprosium-transition-metal interaction in Dy(Co,Ni)10Si2 compounds

Abstract The magnetization of DyCo10−xNixSi2 compounds with x = 0, 2, 4 and 6 has been measured at 4.2 K in magnetic fields up to 38 T and between 4.2 K and room temperature in fields up to 5 T on single-crystalline powder particles which were free to be oriented by the applied field. The strength of the magnetic coupling between the Dy sublattice and the transition-metal sublattice is derived from the high-field magnetization at 4.2 K and, for the compounds with x = 4, also from the field-dependence of the magnetization at the compensation temperature. The results are discussed.