Showing papers on "Curie–Weiss law published in 1982"
TL;DR: In this paper, the authors report detailed measurements of the magnetization of Cu/Ni composition modulated foils as a function of temperature, magnetic field, composition wavelength, and composition amplitude.
Abstract: We report detailed measurements of the magnetization of Cu/Ni composition modulated foils as a function of temperature, magnetic field, composition wavelength, and composition amplitude. We find a Curie temperature that initially increases rapidly with wavelength but quickly saturates. We also find that the Curie temperature is independent of composition amplitude which we ascribe to the existence of disk‐like Ni clusters.
72 citations
TL;DR: In this paper, the effect of the electron-phonon interaction makes the temperature dependence of the spin susceptibility Curie-Weiss-type, with the Curie temperature much lower than in the Stoner theory.
Abstract: Starting from a consideration of how the phonon frequency would change with the spin splitting of the conduction-electron energy bands in an itinerant-electron ferromagnet, we find that in the paramagnetic region the effect of the electron-phonon interaction makes the temperature dependence of the spin susceptibility Curie-Weiss-type, with the Curie temperature ${T}_{C}$ much lower than in the Stoner theory. Further, for $Tl{T}_{C}$ we find that the phonon effect on magnetization can be large enough to account for the anomalous temperature dependence of spontaneous magnetization often observed in itinerant-electron ferromagnets, especially in Invar alloys. To confirm such a conclusion, with the same model and approximation we discuss also the very closely related problem of the magnetic field effect on the sound velocity in an itinerant-electron ferromagnet, and our theory is found to explain satisfactorily the varied observed results for both $Tg{T}_{C}$ and $Tl{T}_{C}$.
56 citations
TL;DR: In this paper, the structure and magnetic properties of TlCrX2 (X= S, Se, Te), Tl3CrS3, TlCl5S8 and AgCrO2 have been investigated.
38 citations
TL;DR: For 3D metals, the atomic moments derived from Curie-Weiss susceptibility are often significantly larger than the value obtained in the ferromagnetic state from the saturation magnetization.
Abstract: For 3d metals the atomic moments derived from Curie‐Weiss susceptibility are often significantly larger than the value obtained in the ferromagnetic state from the saturation magnetization Indeed the Heisenberg model is known to be inappropriate for metallic systems which in general are better described by band theory The ground state properties of metallic magnets, particularly the occurrence of nonintegral moments, are well accounted for using the Stoner theory, but the model is less satisfactory at elevated temperatures The persistence of spin waves above TC and the observation of paramagnetic moments indicate that the 3d band remains split in the paramagnetic phase in contradiction with mean field theory A direct way of establishing the existence of paramagnetic moments is by the paramagnetic scattering of neutrons The technique is particularly enhanced if polarization analysis is employed to obtain a unique estimate of the magnetic cross section In the present paper, we report the results of re
36 citations
TL;DR: In this paper, a general relation between the pressure dependence of the Curie temperature and spontaneous magnetisation is derived in a simple band model, as calculated from the observed values of the pressure dependences of the spontaneous magnetization.
33 citations
TL;DR: In this paper, the crystal and magnetic properties of the Dy(Fe x Al 1-x ) 2 (0≤ x ≤ 10) system were investigated with the X-ray, magnetometric and Mossbauer effect methods.
24 citations
TL;DR: Magnetisation measurements parallel and perpendicular to the applied field are reported for single crystals of ferromagnetic NdAl2 and PrAl2 in the range 4.2-200K and for magnetic fields up to 8.00 T applied in the (100) direction and directions near to (110) and (111) as mentioned in this paper.
Abstract: Magnetisation measurements parallel and perpendicular to the applied field are reported for single crystals of ferromagnetic NdAl2 and PrAl2 in the range 4.2-200K and for magnetic fields up to 8.00 T applied in the (100) direction and directions near to (110) and (111). A quantitative description of the magnetisation is given in terms of a two-dimensional molecular field theory using two crystal-field parameters and the molecular field constant. Below the Curie temperature a satisfactory agreement between theory and experiment is obtained.
19 citations
TL;DR: In this article, the magnetic susceptibility for 14.3 at.% Mn and 14.5 at% Co aluminosilicate glasses has been measured via a sensitive pendulum magnetometer from 4 to 300 K in a field of 5 kOe.
Abstract: The magnetic susceptibility for 14.3 at.% Mn and 14.3 at.% Co aluminosilicate glasses has been measured via a sensitive pendulum magnetometer from 4 to 300 K in a field of 5 kOe. For temperatures above 80 K a Curie–Weiss law was obeyed in both systems; however, below 80 K strong deviations from this law occurred. From the high‐temperature inverse susceptibility, a Bohr magneton number p0 of 5.93 μB for Mn and 4.73 μB for Co was found. These values correspond to the free ion values observed for Mn++ and Co++, respectively. The paramagnetic Curie temperatures ϑ are −117 K for Mn and −44 K for Co. Assuming a cubic closed packed structure to represent our amorphous system, we have analyzed these results with a canonical ensemble for all possible states of the first eleven configurations in which magnetic impurities can be grouped in this structure. Thereby we can explain the deviations from the Curie–Weiss law, ϑ, and p0 and their temperature dependences with nearest neighbor and next nearest neighbor exchanges of −27 and −20 K for Mn and −24 and +5 K for Co.
18 citations
TL;DR: In this paper, mixed Heusler alloys with composition (Ni 1− x Co x ) 2 MnSn (x = 0-1) were prepared and magnetic measurements were undertaken in the ferromagnetic and paramagnetic regions.
17 citations
TL;DR: In this paper, it was shown that the energy loss of 620- and 942-keV electrons in barium titanate and triglycine sulphate is anomalously high at the Curie temperature.
Abstract: Experimentally it is found that the energy loss of 620- and 942-keV electrons in barium titanate, as well as that of 942-keV electrons in triglycine sulphate, is anomalously high at the Curie temperature. The energy loss is also noticeably smaller in the ferroelectric state than in the paraelectric state.
14 citations
TL;DR: In this paper, heat capacity (0.5-20 K) and magnetic-susceptibility (4-300 K) measurements have been made on two cerium sulfide samples having compositions as CeS/sub 1.393/ and CeS 1.457/.
Abstract: Heat-capacity (0.5--20 K) and magnetic-susceptibility (4--300 K) measurements have been made on two cerium sulfide samples having compositions as CeS/sub 1.393/ and CeS/sub 1.457/. These materials follow the Curie-Weiss law above 100 K, and become ferromagnetically ordered near 6 and 3 K, respectively. Shift of the ordering to higher temperatures under applied magnetic fields is also observed in CeS/sub 1.457/. The estimated effective magnetic moment and entropy associated with the ordering are consistent with the paramagnetic nature of Ce/sup 3 +/ (4f/sup 1/) in a crystalline environment.
TL;DR: Using inelastic neutron scattering, this paper studied the magnetic excitations in HoNi2 and showed that although the nickel is not magnetic, it could contribute to the magnetic ordering, which led to a calculated Curie temperature much smaller than the experimental one.
Abstract: Using inelastic neutron scattering we have studied the magnetic excitations in HoNi2. Several modes have been observed in the [001] direction showing that the magnetic excitations in this compound are governed by crystal field effects. The acoustic mode is the only one which is weakly dispersive. The JHo‐Ho interaction deduced is very weak and leads to a calculated Curie temperature much smaller than the experimental one. This shows that although the nickel is not magnetic it could contribute to the magnetic ordering. An analysis of the complete results in terms of crystalline electric field and Heisenberg type exchange interaction fails to account simultaneously for magnetization and inelastic neutron measurement.
TL;DR: In this article, magnetic properties of holmium iron garnet (HoIG) have been studied in magnetic field up to 150kOe applied parallel to the main crystallographic directions in the 4.2-300K temperature range.
Abstract: On single crystals of holmium iron garnet (HoIG), magnetic properties have been studied in magnetic field up to 150kOe applied parallel to the main crystallographic directions in the 4.2–300K temperature range. Above 130 K, the magnetization is isotropic and linear magnetic field dependent as previously found in polycrystals and predicted by Neel's ferrimagnetic theory. Nevertheless the paramagnetic Curie temperature is much higher than the polycrystal value. Below 130K, due to the onset of the umbrella structure, the ferrite magnetization presents a non linear field variation with [111] as easy direction. The field evolutions of the anisotropy constants (K
1 andK
2) were calculated. Optical absorption measurements of both 58→5I
6 and 5I
8→5I
7 transitions are reported and compared to the results of the literature in terms of inequivalent magnetic sites.
TL;DR: In this paper, the structure and magnetic properties of Y(Al1−xFex)12 intermetallic compounds were studied by Mossbauer spectroscopy and magnetization measurements.
Abstract: In order to investigate the magnetic behavior of 3d atoms in the ThMn12‐type structure, the structured and magnetic properties of Y(Al1−xFex)12 were studied by Mossbauer spectroscopy and magnetization measurements. The Y(Al1−xFex)12 intermetallic compounds crystallize in the ThMn12‐type structure for x in the range of 0.3–0.5. The results can be explained on the basis of the preferential atomic ordering observed in the ternary compounds. The compounds are ferromagnetic with Curie temperatures of 130, 170, and 280 K, respectively, for x values of 0.3, 0.4, and 0.5.
TL;DR: In this paper, the cation distribution of the solid solution CdCr2xIn2•2xS4 was determined by Mossbauer spectroscopy on 57Fe doped samples.
Abstract: The cation distribution of the solid solution CdCr2xIn2‐2xS4, was determined by Mossbauer spectroscopy on 57Fe doped samples. At high temperature the susceptibility follows a Curie‐Weiss law. The low temperature field dependence of the magnetization shows that the samples 0.90≤x≤0.98 are ferromagnetic. In the range 0.25≤x≤0.98, irreversible behaviour, remanent and time dependent magnetization are observed. Magnetization and EPR results on the sample x=0.60 are consistent with the spin glass behaviour found by dc susceptibility measurements.
TL;DR: In this article, the authors examined the relationship between the magnetic homogeneity and the structural order parameter S. The A•N plots for the alloys with S = 0 and 1 lie on parallel straight lines, being satisfactorily expressed by Eq. (1).
Abstract: Arrott and Noakes have proposed the following equation of state for the magnetization near the Curie temperature: M1/β = A(T−TC)+B(H/M)1/γ⋅⋅⋅(1), where 1/β = 2.5 and 1/γ = 0.75. In the present report, the M2.5 vs (H/M)0.75 plots (A‐N plots) for ordered and disordered Fe72Pt28 alloys are examined in order to clarify the relationship between the magnetic homogeneity and the structural order parameter S. The A‐N plots for the alloys with S = 0 and 1 lie on parallel straight lines, being satisfactorily expressed by Eq. (1), since the ideally disordered alloy is magnetically homogeneous as well as the perfectly ordered alloy. On the other hand, the magnetizations of the alloys with 0
TL;DR: In this paper, the temperature dependence of the narrow EPR line with an isotropic value of g = 2.002 has been investigated in a semi-insulating GaAs:Cr sample.
Abstract: The temperature dependence, over the 4.2–100 K range, of the narrow EPR line, labeled X, with an isotropic value of g = 2.002 has been investigated in a semi‐insulating GaAs:Cr sample. From its Curie‐Weiss behavior, leading to a (T+13.1)−1 law, it is concluded that it may result from antiferromagnetic exchange coupled spins, originating from dangling bonds located on extended defects present in the crystal.
TL;DR: In this article, it was shown that the linear term in the temperature dependence of paramagnetic susceptibility arises due to singularity in the density of states g(ϵ) near the Fermi energy.
TL;DR: In this article, the results of magnetic measurements performed on 20Fe2O380[3B2O3(1−χ)PbOχAs 2O3] glasses, in the temperature range 4.2 to 300 K are reported.
Abstract: The results of magnetic measurements performed on 20Fe2O380[3B2O3(1−χ)PbOχAs2O3] glasses, in the temperature range 4.2 to 300 K are reported. By decreasing the temperature a downward curvature of reciprocal susceptibility is observed for T<50 K. The composition dependence of the paramagnetic Curie temperatures and Curie constants is discussed.
TL;DR: In this article, the temperature dependence of specific heat in the vicinity of the first-order reentrant superconducting-ferromagnetic transition was computed by means of a simple model from the temperature dependent of the spontaneous magnetization of the Ho ions and was found to be in good agreement with the experimental data.
Abstract: Analysis of neutron diffraction data on the compound (Ho0.6Er0.4)Rh4B4 indicates that the Curie temperature is depressed by about 0.2 K, due to the occurrence of superconductivity, in agreement with theoretical predictions. The temperature dependence of the specific heat in the vicinity of the first-order re-entrant superconducting-ferromagnetic transition was computed by means of a simple model from the temperature dependence of the spontaneous magnetization of the Ho ions and was found to be in good agreement with the experimental data.
TL;DR: In this paper, the influence of the permanent magnetic field on the dielectric properties of Sn2P2S6 single crystals has been investigated near the ferroelectric phase transition.
Abstract: The influence of the permanent magnetic field on the dielectric properties of ferroelectric-semiconductor Sn2P2S6 single crystals has been investigated near the ferroelectric phase transition. It is found that the value of Curie temperature shift ΔTc depends on the orientation Ps[101] respectively to the magnetic field. Maximum ΔTc for the annealed sample is 0.2° for H = 23 kG. Accordingly to results of dielectric measurements the phase transition in Sn2P2S6 is referred to the first order. The shift of Tc is connected with the interaction of the moving phase boundary with the magnetic field.
TL;DR: In this paper, the effects of Ising anisotropy on Curie temperature have been studied in the presence of single ion anisotropic for a spin S ǫ = 1 system.
Abstract: Effects of Ising anisotropy on Curie temperature have been studied in the presence of single ion anisotropy for a spin S = 1 system. The Green function technique with random phase approximation has...
TL;DR: In this paper, a peak of high magnetic susceptibility with respect to Fe concentration was found centered at the ferro-antiferro critical composition (about 15 at%), indicating the existence of a wide concentration region where the orientation of Fe moment is unstable.
Abstract: High field magnetic susceptibility for Cr–Fe alloy with Fe concentration from 5.0 to 29.9 at.% has been measured at 4.2 K by using a pulsed magnetic field up to 360 kOe. A round peak of high field magnetic susceptibility with respect to Fe concentration has been found centered at the ferro-antiferro critical composition (about 15 at.%). This result indicates the existence of a wide concentration region where the orientation of Fe moment is unstable.
TL;DR: In this article, the frequency dependence of the ac magnetic susceptibility of iron whiskers and nickel platelets in the region of the Curie temperature was investigated and it was shown that a particular form of a magnetic memory function can be used in formulations based on either or both magnetic viscosity and/or relaxation toward equilibrium.
Abstract: Linear response theory is applied to the frequency dependence of the ac magnetic susceptibility of iron whiskers and nickel platelets in the region of the Curie temperature. It is shown that a particular form of a magnetic memory function can be used in formulations based on either or both magnetic viscosity and/or relaxation toward equilibrium. This memory function corresponds to a relaxation rate that follows a power law in time as proposed by Ngai and White.
TL;DR: In this article, the effects of biquadratic exchange interaction and the uniaxial anisotropy on the curie temperature of the Heisenberg Ferromagnet with spin-one has been studied.
Abstract: The effects of biquadratic exchange interaction and the uniaxial anisotropy on the curie temperature of the Heisenberg Ferromagnet with spin-one has been studied. Green function technique with random phase approximation has been used. The variation of curie temperature with biquadratic and anisotropic parameters for different lattices has been discussed.
TL;DR: The magnetic susceptibilities of single crystal dysprosium and terbium-50% holmium have been measured in their paramagnetic phases and the effect of annealing has been investigated and heating the sample to 360 K for ≈ 18 h causes ≈ 4% reduction in χ273.
TL;DR: In this paper, the transition temperature for the square-lattice Ising ferromagnet with first-, second-and third-neighbour interactions is calculated by the interface method.
Abstract: The transition temperature for the square-lattice Ising ferromagnet with first-, second- and third-neighbour interactions is calculated by the interface method. The results are apparently fairly accurate, except when the third-neighbour coupling is completely dominating. The author checks in particular, a series result for the equivalent-neighbour model to within a few per cent.
TL;DR: In this article, the authors considered the Valenta model of a thin ferromagnetic film in the critical region above the Curie point and obtained spatial and temperature dependence for spin correlation time and magnetic susceptibility.
TL;DR: In this paper, the spatial distribution and temperature dependence of spin correlation time in a thin ferromagnetic film near the Curie temperature were considered, and the spin correlation was analyzed.