Showing papers on "Curie–Weiss law published in 1969"
TL;DR: In this article, the magnetic properties and lattice parameters for 13 compounds of the composition RIn3 (Cu3Au structure) are reported and the magnetic measurements have been performed between 4.2° and 500°K with magnetic fields up to 30 kOe.
Abstract: The magnetic properties and the lattice parameters for 13 compounds of the composition RIn3 (Cu3Au structure) are reported. The magnetic measurements have been performed between 4.2° and 500°K with magnetic fields up to 30 kOe. With the exception of compounds with R=La, Sm, Y, and Yb Curie–Weiss behavior is observed in the high‐temperature region. At low temperatures the magnetic behavior for compounds in which R=Ce, Nd, Sm, Gd, Tb, Dy, Ho, and Er is ascribed to antiferromagnetic ordering. In the case of PrIn3 magnetic ordering is prevented by crystalline fields. The splitting of the J = 4 state of Pr3+ by cubic crystalline fields has been calculated for various combinations of fourth‐ and sixth‐order potentials. Possible energy diagrams are presented.
143 citations
79 citations
TL;DR: In this paper, the variation of the critical temperature (the Curie or Neel temperature) of a magnetic crystal randomly diluted with non-magnetic atoms is evaluated as a function of concentration p of magnetic atoms by the effective Hamiltonian method based on the Ising and the Heisenberg models.
Abstract: The variation of the critical temperature (the Curie or Neel temperature) of a magnetic crystal randomly diluted with non-magnetic atoms is evaluated as a function of concentration p of magnetic atoms by the effective Hamiltonian method based on the Ising and the Heisenberg models. The specific heat of Ising ferromagnet above the Curie temperature is calculated for various concentrations in order to see the existence of Schottky-type maximum. The critical index of susceptibility and the Curie temperature for diluted ferromagnet is also calculated using Pade approximation to check the idea that the lowering of the Curie temperature with the decrease of p is attributed to the decrease of effective dimensionality of ferromagnetic system.
68 citations
TL;DR: The static magnetization of the family of compounds La1−xPbxMnO3(0.25) has been measured from close to absolute zero to about 800 °K.
Abstract: The static magnetization of the family of compounds La1−xPbxMnO3(0.25 < x < 0.45) has been measured from close to absolute zero to about 800 °K. The compounds are ferromagnetic, with Curie temperat...
45 citations
36 citations
TL;DR: The magnetic susceptibilities for neodymium, gadolinium and dysprosium germanides and silicides were measured between about 60° to about 700°K as mentioned in this paper.
Abstract: The magnetic susceptibilities for neodymium, gadolinium and dysprosium germanides and silicides were measured between about 60° to about 700°K. Plots of 1/χ vs T show a Curie‐Weiss behavior, but deviations from it are observed below room temperature. The deviations become smaller with decreasing temperature and in most instances tend to approach the asymptote just above the transition temperature. These compounds have the D88 structure and a ferromagnetic spin ordering for rare earth atoms in the crystallographic 6(g) sites, and an antiferromagnetic ordering in the 4(d) sites is consistent with the observed behavior.
31 citations
TL;DR: In this article, the authors studied the direction of easy magnetization in Gd as a function of temperature and pressure, and discussed the angle of deviation in terms of the (small) anisotropy constants resulting from the weak crystalline field.
Abstract: The direction of easy magnetization in Gd is studied as a function of temperature and pressure. The pertinent experimental results have already been given by Robinson, Milstein, and Jayaraman. A Gd sample was used as the core of a small transformer; a constant input voltage was supplied to this transformer. The secondary voltage was monitored as a function of temperature at several constant pressures. The secondary voltage of the transformer, being proportional to the permeability of the sample, is a sensitive indicator of changes in magnetic structure in the Gd sample. Typically, the secondary voltages behave as follows as the temperature of the transformer is lowered: A sharp rise in the secondary voltage occurs at the Curie temperature, followed by another sharp rise at a temperature well below the Curie point. The magnitude of the secondary voltage at this latter transition is from two to three orders of magnitude greater than at the transition from the paramagnetic to the ferromagnetic state. This transition is interpreted as a magnetic transition in which the direction of easy magnetization in Gd deviates from the $c$ axis. The angle of deviation is discussed in terms of the (small) anisotropy constants resulting from the weak crystalline field in Gd. In terms of the output voltage, one is able to obtain the relative deviations of the direction of easy magnetization from the $c$ axis. The temperatures, as a function of pressure, at which the maximum deviations occur can also be obtained. As the temperature is lowered further, the direction of easy magnetization starts to approach the $c$ axis again. Comparisons are made with other measurements of this angle of deviation.
27 citations
24 citations
TL;DR: In this article, a Co-Pt 50-50 single crystal was quenched very rapidly and subsequently annealed in the range 200-750°C in the presence of a magnetic field.
Abstract: A Co-Pt 50-50 single crystal annealed at 950°C was quenched very rapidly and subsequently annealed in the range 200-750°C in the presence of a magnetic field. For annealing temperatures below the Curie temperature, an analysis of the induced magnetic anisotropy detects both directional ordering and the onset of long range ordering. If the magnetic field is directed along one of the fourfold axes of the initially disordered crystal, a uniaxial anisotropy is detected due to a preferential development of the ordered regions having their tetragonal axis parallel to the direction of the magnetic field. Although this effect is weak below the Curie temperature due to the low diffusion rate, it is sufficient to determine the later development of order at higher temperatures. After such a heat treatment up to 750°C, the analysis of the magnetization curves and a study of the neutron diffraction pattern show that the entire specimen consists of practically one single-ordered region having its tetragonal axis in the direction of the applied magnetic field.
21 citations
TL;DR: In this paper, the Curie temperature and electrical resistivity at 4.2°, 78°, and 300°K have been measured for nickel-carbon solid solutions containing up to 1.5 at.% carbon.
Abstract: The Curie temperatures and the electrical resistivity at 4.2°, 78°, and 300°K have been measured for nickel‐carbon solid solutions containing up to 1.5 at.% carbon. The resistivity at 4.2°K increases at the rate 3.48±0.06 μΩ cm/at.% carbon; whereas the Curie temperature decreases by ∼30 C°/at.% carbon. The electrical resistivity shows positive apparent deviations from Matthiessen's rule. The variation of the Curie temperature is consistent with donor theories in which carbon donates both its p electrons to the d band of the metal. The susceptibility shows an unusually large field dependence near the Curie temperature presumably because of as yet unclassified modifications of the nickel moment due to the presence of carbon.
12 citations
TL;DR: The magnetic susceptibility and electrical resistivity of uranium phosphides and UP-ThP solid solutions were measured in this article, and the Neel point and the Weiss constant θ were estimated.
Abstract: The magnetic susceptibility and electrical resistivity of uranium phosphides and UP-ThP solid solutions were measured. All the uranium phosphides exhibited paramagnetism at room temperature, and followed the Curie-Weiss law. The Neel point TN for UP2 and UP, and the Weiss constant θ were estimated. Ferromagnetic components made their appearance in UP2 and UP, in the temperature range below TN. With UP-ThP solid solutions, the changes according to composition observed in the values of TN and θ indicated that UP is magnetically diluted by ThP, which latter compound is characterized by Pauli paramagnetism, and whose presence contributes to diminish the exchange interactions. The electrical resistivity of UP increased rather rapidly with temperature up to a point corresponding to TN beyond which the tendency changed sharply to a slightly negative coefficient. ThP showed a consistently low value of resistivity, were slowly rising with temperature, and that of UP-ThP solid solutions revealed a behavior intermed...
TL;DR: The APM-FM transition in Au2Mn has been induced at zero field by the application of hydrostatic pressure as discussed by the authors, and the transition pressure is independent of temperature.
TL;DR: In this paper, the results of the 27Al NMR were discussed in terms of the Ruderman-Kittel-Kasuya-Yosida theory and the magnetic susceptibilities were measured in the temperature region from 300 down to 4.2°K, and found to deviate from Curie-Weiss laws only for temperatures lower than 40°K.
Abstract: The Knight shifts of the 27Al NMR in Pr3Al11, Nd3Al11, and EuAl4 have been measured between 86 and 300°K, and have been found to be different for inequivalent Al sites. The results are discussed in terms of the Ruderman–Kittel–Kasuya–Yosida theory. The magnetic susceptibilities have been measured in the temperature region from 300 down to 4.2°K, and found to deviate from Curie–Weiss laws only for temperatures lower than 40°K.
TL;DR: In this paper, the magnetic contribution to the specific heat in the vicinity of the Curie temperature is calculated in the molecular field approximation for a two-sublattice material.
Abstract: Using the Neel model for a two-sublattice material, the magnetic contribution Cm to the specific heat in the vicinity of the Curie temperature is calculated in the molecular field approximation. At the Curie temperature the calculation reveals a discontinuity ΔCm in the specific heat, which is evaluated and compared with experiment. The theoretical and experimental values are in good agreement for Zn0.38Mn0.62Fe2O4 and Zn0.5Ni0.5Fe2O4 as measured by Verhaeghe et al, and for MnFe2O4, measured in the present work. The agreement is less satisfactory in the case of Zn0.5Mg0.5Fe2O4 as measured by Shulga (1957).
TL;DR: The susceptibility of Al 3 V has been measured between 0.4 and 293°K and has been found to satisfy a Curie-Weiss expression with a critical temperature of ≈ -65°K as discussed by the authors.
TL;DR: Magnetic susceptibility data suggest that the crystal field splittings of the 4f levels of Ce and Pr impurities are larger in metallic YB6 than in isostructural and semiconducting SrB6, contrary to what might be expected.
TL;DR: In this article, a localized model was proposed to estimate the coerciveness of ordered Au4V with a coercive force of 23 kOe at 4.2°K and a ferromagnetic moment of 0.80 microB/V at.
TL;DR: In this paper, it was shown that the usual theory of indirect exchange in insulators is incapable of accounting for the increase of paramagnetic Curie temperature in EuO:La3+.
TL;DR: In this article, the authors analyzed the Weiss and Forrer data for nickel and showed that the overall thermodynamic potential is not homogeneous although the scaling laws are satisfied for each phase.
TL;DR: In this paper, the magnetic susceptibility of dilute magnetic alloys of Mn in Rh and Fe in a Nb-Mo solid solution deviates from the Curie-Weiss law, and the following temperature dependence is observed: Δχ = C/(T + TK) + α log (TK/T), with α ≡ 0 for T > TK0.
TL;DR: In this article, an extension of molecular field theory to magnetic susceptibility of randomly dilute systems is presented, and a useful expression involving the paramagnetic Curie temperature θ of the pure system is obtained.
TL;DR: In this paper, the Bethe-Peierls-Weiss method was used to derive the exchange energy and the effective field for iron in the neighborhood of the Curie temperature.
Abstract: Equations with and without an external magnetic field were derived by using the Bethe-Peierls-Weiss method for the exchange energy and the effective field for iron. The numerical values for both the exchange energy and the effective field were obtained in the neighborhood of the Curie temperature. It was found that the external magnetic field does influence the exchange energy, and the critical point of the exchange energy at the Curie temperature vanishes if an external magnetic field is applied.