Showing papers on "Curie–Weiss law published in 1986"
TL;DR: The origin of the Curie-Weiss law of the magnetic susceptibility universally observed in ferromagnetic materials is discussed from a point of view that the local spin fluctuation amplitude is almost conserved as discussed by the authors.
Abstract: The origin of the Curie-Weiss law of the magnetic susceptibility universally observed in ferromagnetic materials is discussed from a point of view that the local spin fluctuation amplitude is almost conserved. A fully consistent treatment is presented which can deal with both the ordered phase and the paramagnetic phase on an equal footing. In the case of weakly ferromagnetic limit, Rhodes-Wohlfarth plot is revised from a new stand point. In the ordered phase, observed systematic trends of magnetization curves are explained in connection with the nature of dynamical spin fluctuation spectra. Some new interesting relations among various magnetic data are derived and compared with experiments. Temperature dependence of magnetic susceptibilities of Fe and Ni is also discussed.
176 citations
TL;DR: In this paper, the effect of substitution of R by Zr on saturation magnetization, Curie temperature and anisotropy is presented, showing a decrease in magnetic moment and temperature but an increase in anisotropic field.
61 citations
TL;DR: Magnetic susceptibility studies on single crystals of nearly stoichiometric La2NiO4 with the applied field both parallel and perpendicular to the c axis show a transition at 204 K below which two-dimensional canted antiferromagnetic order seems to exist as mentioned in this paper.
56 citations
55 citations
TL;DR: In this article, exact expressions for the Curie temperature, magnetization, quadrupolar moment and the susceptibility of a spin-one Ising model on a Bethe lattice are derived.
Abstract: Exact expressions for the Curie temperature, magnetization, quadrupolar moment and the susceptibility of a spin-one Ising model on a Bethe lattice are derived. Biquadratic exchange and single-ion anisotropy are included, in addition to the bilinear exchange interactions. The variation of the critical temperature with the relative strengths of these interactions is studied. The expressions for the magnetization and quadrupolar moment are compared, where possible, to those previously reported for Ising systems on a Bethe lattice. The equivalence of our results with those obtained by a generalized constant-coupling approximation applied to a spin-one Ising model on a regular lattice is demonstrated. The magnetization curves and the thermal variation of the quadrupolar moment are studied in depth for a range of interaction parameters where unusual features appear because of the presence of an anti-Curie temperature. The temperature variation of the zero field susceptibility is also studied in this region.
41 citations
TL;DR: In this article, the magnetocaloric effect (MCE) was measured on a polycrystalline gadolinium sample in a 0.5 s pulsed field up to 70 kOe at temperatures from 80 to 360 K. The results obtained from the measurements were used to calculate the MCE in said samples and to plot the equal magnetization lines.
39 citations
TL;DR: In this paper, the Curie temperature and its pressure effect of Fe-Nd and Fe-nd-B amorphous alloys were investigated and it was shown that the concentration dependence curve exhibits a broad maximum around 30% Nd. These magnetic properties are hardly affected by addition of B.
20 citations
TL;DR: In this article, the magnetic susceptibilities of Sc/sub y/U/sub 1-y/O/sub 2+x/ solid solutions have been measured from 2.7 K to room temperature.
15 citations
TL;DR: In this paper, it was shown that the zero-field suscetpibility χ of many ferromagnets may be described with high accuracy by a modified power law (generalized Curie-Weiss law) χT ∼ [(T − TC)/T]−γc in the whole paramagnetic regime, where γc is the critical susceptibility exponent.
Abstract: It is shown that the zero-field suscetpibility χ of many ferromagnets may be described with high accuracy by a modified power law (generalized Curie-Weiss law) χT ∼ [(T – TC)/T]−γc in the whole paramagnetic regime, where γc is the critical susceptibility exponent. In contrast, the conventional power law χTC ∼ [(T – TC)/TC]−γc holds only for the very small critical regime. Application of the scaling variable (T – TC)/T, which is non-linear in T, to other physical situations (spin glasses, percolation) is discussed. Altogether the temperature range where scaling ideas are useful appears to be much wider than generally expected.
12 citations
12 citations
TL;DR: In this paper, the variation with modulation wavelength of the Curie temperature of a Heisenberg magnetic superlattice is studied in the molecular field approximation and in the continuum limit.
TL;DR: In this article, a simple method for describing the basic magnetic properties of diluted ferromagnetic alloy with S = 1 2 is discussed for the case of a Heisenberg approximation for a simple cubic lattice.
TL;DR: In this article, a systematic study of the magnetic properties of Fe-Sc amorphous alloys has been carried out for the first time, and the average magnetic moment is larger than that of FeZr and Fe-Ti amorphus alloys, which is in conformity with the results obtained by band calculations.
Abstract: A systematic study of the magnetic properties of Fe-Sc amorphous alloys has been carried out for the first time. The samples were prepared by dc high-rate sputtering. The average magnetic moment is larger than that of Fe-Zr and Fe-Ti amorphous alloys. This trend is in conformity with the results obtained by band calculations. The difference in magnitude between calculated and observed magnetic moments in Fe-early transition metals is explained by taking into account the contraction of atomic distance. The thermal expansion anomaly associated with the spontaneous volume magnetostriction ω s is more pronounced with decreasing Sc content and the shrinkage is observed even above the Curie temperature. The Curie temperature exhibits the highest value around 20% Sc. The pressure shift of the Curie temperature is also significantly large, reflecting a large value of ω s . The pressure coefficient of the Curie temperature (1/T c )(dT c /dP) varies linearly with the Curie temperature, and its sign changes around 20% Sc. The striking thermal expansion anomaly above T c , and the linear relationship between (1/T c )(dT c /dP) and T c imply that the present Fe-Sc amorphous alloys are magnetically inhomogeneous.
TL;DR: In this article, the effect of crystal-field anisotropy on the Curie temperature was studied in an S = 1 anisotropic Heisenberg-Ising ferromagnet.
TL;DR: Amorphous alloys have been prepared by melt quenching technique and their magnetization measurements have been made over the temperature range from 77 to 800 K in this paper, where the observed ratio of the spinware stiffness constant to the Curie temperature 0.15 meV A -1 is nearly independent of Mn concentration, from which the localized electron nature characterizing the nearest neighbor interaction is preferred in the present alloys.
TL;DR: In this article, it is demonstrated that in order to account for the variation of the Curie temperature of gadolinium with pressure, it is essential to include details of the Fermi surface structure.
TL;DR: In this article, the Curie temperature was determined from a resistivity measurement of a nickel sample, and the result was compared to that obtained from a method previously described in this Journal.
Abstract: The Curie temperature is determined from a resistivity measurement of a nickel sample, and the result is compared to that obtained from a method previously described in this Journal In addition, the Curie temperature is determined for nickel and Monel 400 using a tunnel diode oscillator Data analysis includes a method to calculate a critical point exponent
TL;DR: In this article, the free energy of the site-dilute antiferromagnetic Ising model in the presence of a uniform magnetic field was computed using a method proposed by van Hemmen.
TL;DR: In this article, the field dependence of optical absorption of the R' line is measured for H 0 | c and the magnetization process is observed on the complicated antiferromagnet YbCrO 3 in pulsed high magnetic field.
TL;DR: In this paper, a thermodynamic model of phase transitions in ferroelectric ceramics is suggested and the behavior of the basic physical properties of the system with respect to microstructure (grain size, pore density, etc.) and Ferroelectric characteristics (polarization, dielectric constant, Curie Weiss constant) are discussed in the cases of 1st and 2nd order phase transitions.
Abstract: A thermodynamic model of phase transitions (PT) in ferroelectric ceramics is suggested and the behavior of the basic physical properties of the system with respect to microstructure (grain size, pore density, etc.) and ferroelectric characteristics (polarization, dielectric constant, Curie Weiss constant, etc.) are discussed in the cases of both 1st and 2nd order phase transitions. The model is based on geometric and dimensional effects which occur in ferroic systems and assumes ceramics as a single domain matrices consisting of grains and pores.
TL;DR: Magnetic susceptibility was measured on the samples of U1-xGdxO2 prepared by a coprecipitation method from 1.7 K to room temperature as mentioned in this paper.
Abstract: Magnetic susceptibility was measured on the samples of U1-xGdxO2 prepared by a coprecipitation method from 1.7 K to room temperature. The behavior of magnetic susceptibility is contributed almost from trivalent gadolinium ion because of its very large spin magnetic moment of 8S. For x<40%, the magnetic susceptibility-temperature curve obeyed Curie-Weiss law and values of magnetic susceptibility increase linearly with increasing gadolinium concentrations. For the higher concentrations of gadolinium the magnetic susceptibility-temperature curve has a peak at 34 K, showing a magnetic field dependence of magnetic susceptibility at liquid helium temperature which would be expected for the case of a weak magnetic anisotropy in antiferromagnets.
15 Apr 1986
TL;DR: In this paper, the authors reported a single Lorentzian absorption with a relatively narrow linewidth and freeelectron g-value for four hot-pressed boron-rich Boron carbide samples B1−xCx in the composition range 01≤x≤02 at 2 K.
Abstract: Electron spin resonance (ESR) spectra are reported for four hot‐pressed boron‐rich boron carbide samples B1−xCx in the composition range 01≤x≤02 At 2 K the spectra for all four compositions are characterized by a single Lorentzian absorption with a relatively narrow linewidth and free‐electron g‐value The B4C ESR linewidth remains narrow between 2 and 295 K, while the linewidth of the other three samples containing less carbon increases by a factor of 20 over this temperature range Above 20 K the ESR signal in the latter three samples has a lineshape that cannot be described by a single Lorentzian, but can be explained as the sum of two Lorentzians with different linewidths, suggesting the presence of two distinct paramagnetic centers The integrated intensities of the ESR signals in all samples follow a Curie law below 100 K, and the Currie constant corresponds to spin concentrations of 2 to 3×1019 per gram While these values are in agreement with static magnetic susceptibility data for samples cut from the same hot‐pressed element, they are approximately two orders of magnitude less than the carrier densities estimated from transport measurements This suggests that the carriers are spinless bipolarons
TL;DR: In this paper, a refined method for preventing the incorporation of oxygen into Chevrel compounds is presented, which has been used in producing Cu1.8Mo6S8, SnMo6s8, and PbMo 6S8.
Abstract: A refined method for preventing the incorporation of oxygen into Chevrel compounds is presented. This method has been used in producing Cu1.8Mo6S8, SnMo6S8, and PbMo6S8. The removal of oxygen enhances the magnetic susceptibility of these materials as well as raising their superconducting transition temperatures. The curves of magnetic susceptibility versus temperature show structures that may indicate lattice deformations.
TL;DR: In this article, the thickness dependence of the magnetization and the Curie temperature has been calculated for (111)oriented Y3Fe5O12 films using the molecular field theory to compare with the experimental results.
Abstract: The thickness dependence of the magnetization and the Curie temperature has been calculated for (111)‐oriented Y3Fe5O12 films using the molecular field theory to compare with the experimental results. It is found that the sublattice magnetization for a layer, i.e., the local magnetization, changes with depth. The local magnetization changes only four layers from surfaces and is constant for layers inside at room temperature. The average value of the local magnetization with respect to depth, i.e., the magnetization of the film decreases monotonically with decreasing thickness. The Curie temperature is constant down to about 30 A; below that it decreases. The calculated results explain the experimental thickness dependence of Curie temperature and effective anisotropy field within the error.
TL;DR: In this article, the 3D change of the polarization vector of a polarized neutron beam during transmission through a part of a polycrystalline nickel ring has been studied as a function of the time after field reversal in the ring at different temperatures near the Curie temperature.
TL;DR: In this paper, the dilute Ising ferromagnet with a three-atom four-spin interaction was studied by a new effective field theory based on Callen's identity.
TL;DR: In this article, for the antiferromagnetic Ising model on a square lattice with two-dimensional purely dipole interaction, seven terms are calculated in the high-temperature expansions of the susceptibility with respect to an inhomogeneous field with the period of the ground state and of the energy.
Abstract: For the antiferromagnetic Ising model on a square lattice with two-dimensional purely dipole interaction, seven terms are calculated in the high-temperature expansions of the susceptibility with respect to an inhomogeneous field with the period of the ground state and of the energy. The estimate of the critical exponent of the susceptibility with respect to the inhomogeneous field, ..gamma.. = 1.00 +/- 0.05, shows that the model and the Ising model with short range interaction belong to different universality classes. The estimates of the critical temperature and the Curie-Weiss constant differ by more than a factor two from the predictions of the molecular field approximation. The values of the energy and entropy at the critical point indicate that there are strong correlation effects in the paramagnetic phase.
TL;DR: In this paper, a three dimensional polarization analysis was carried out on a polarized neutron beam which passed through a part of a poly-crystalline nickel ring which was positioned in a furnace.
Abstract: Three dimensional polarization analysis was carried out on a polarized neutron beam which passed through a part of a poly-crystalline nickel ring which was positioned in a furnace. From the polarization components, the field, time and temperature dependence of the mean magnetization and the local magnetization in the domains were determined, which delivered very accurate values for the critical exponents β and γ the magnetic anisotropy and detailed information about the magnetization reversal in the critical region of nickel.
TL;DR: In this paper, the magnetic properties of 16.7Fe75.5B7 were investigated using a high pulsed magnetic field system up to 200kOe, and the results showed that the spin reorientation temperature Ts decreases with the increase of x.
Abstract: Using a high pulsed magnetic field system up to 200kOe, we have investigated the magnetic properties of (Nd1-xTbx)16.7Fe75.5B7.8 (x=0, 0.05, 0.1, 0.2, 0.4) at a temperature range 77-450K. The results show that the spin reorientation temperature Ts decreases with the increase of x.