Showing papers on "Curie–Weiss law published in 1973"
TL;DR: In this paper, the effect of spin fluctuations on itinerant electron ferromagnetism was extended to include the ferromagnetic phase and the correction to the Hartree-Fock free energy as a function of magnetization was expressed in terms of the transversal dynamical susceptibilities.
Abstract: The theory of the effect of spin fluctuations on itinerant electron ferromagnetism, which we have developed previously, is extended to include the ferromagnetic phase. The correction to the Hartree-Fock free energy as a function of magnetization is expressed in terms of the transversal dynamical susceptibilities and is actually calculated by using a modified random phase approximation for the dynamical susceptibilities; the random phase approximation is modified so as to give a consistent static limit throughout the whole temperature range covering both below and above the Curie point. As a result, the magnetization at low temperatures shows a T 3/2 dependence due to the spin wave excitations, the Curie temperature is generally lowered from the Stoner (Hartree-Fock) value and the magnetic susceptibility above the Curie temperature shows an approximate Curie-Weiss behavior.
307 citations
TL;DR: In this paper, the optical absorption spectra of HgCr 2 Se 4 single crystals in the intrinsic transition region were measured as a function of magnetic field at a number of fixed temperatures.
Abstract: The optical absorption spectra of HgCr 2 Se 4 single crystals in the intrinsic transition region were measured as a function of magnetic field at a number of fixed temperatures. The absorption edge, 0.80 eV, at room temperature shifted to 0.27 eV at liquid helium temperature. The temperature dependence of the absorption edge was nonlinear and remarkable around the Curie temperature. The absorption edge also shifts to the lower energy side with the increasing magnetic field. The field dependence of the edge shift in weaker magnetic field was larger at the Curie temperature than it in the higher temperature region. The temperature and magnetic field dependence of the absorption edge was compared to a calculated spin correlation function in spinels with the nearest neighbour exchange interaction between localized Cr +3 ions. Other kind of exchange interaction would be required to explain the temperature dependence of the absorption edge.
53 citations
TL;DR: In this article, the crystal structure of KCrS2 has been confirmed and the paramagnetic Curie temperature is +112 K, indicating that the ferromagnetic interaction in the sheets is the dominant one.
47 citations
39 citations
TL;DR: In this article, the effect of atomic ordering on the Curie temperature was discussed by a pair-interaction model and it was concluded that Fe-Fe pair interaction is negative when only the nearest neighbor pair interactions were taken into account.
Abstract: The ferrromagnetic Curie temperatures were measured for ordered and disordered phases of Fe 1- x Pt x (0.25≤ x ≤0.30). The effect of atomic ordering on the Curie temperature was discussed by a pair-interaction model. It was concluded that Fe-Fe pair interaction is negative when only the nearest neighbor pair interactions were taken into account.
36 citations
TL;DR: In this article, it was shown that the value of spontaneous magnetization for the two-dimensional Ising model computed by Onsager is indeed, the appropriate derivative of the free energy with respect to the magnetic field.
Abstract: We show that the value of the spontaneous magnetization for the two-dimensional Ising model computed by Onsager is indeed, the appropriate derivative of the free energy with respect to the magnetic field. The argument is based on a simple application of the duality transformation.
35 citations
35 citations
TL;DR: Magnetic susceptibility measurements have been carried out on single and polycrystalline specimens of lutetium between 1.5 and 300 °K by the Faraday method as mentioned in this paper.
Abstract: Magnetic susceptibility measurements have been carried out on single and polycrystalline specimens of lutetium between 1.5 and 300 °K by the Faraday method. Its susceptibility was found to be paramagnetic and almost independent of temperature. A broad maximum centered at approximately 120 °K was found. Due to the discrepancies in past results of yttrium and lanthanum, their susceptibilities were also measured. Yttrium and lutetium were found to have χa greater than χc. Provided the specimens were of high purity, the relationship χpoly = (2/3)χa + (1/3)χ was well obeyed. Oxygen and hydrogen were found in general to lower the susceptibilities of these metals. The presence of an fcc phase in lanthanum was found to increase its susceptibility relative to a dhcp phase. An estimate of the susceptibility of pure fcc lanthanum is given.
30 citations
29 citations
TL;DR: In this article, the 2nd and 3rd order nonlinear terms against the high frequency magnetic field are derived from the observations of the 2.5 GHz and 3 GHz harmonics, respectively.
Abstract: In order to obtain the information about nonlinear terms of the high frequency magnetic susceptibility at 2MHz near the Curie temperature the 2nd and 3rd order nonlinear terms against the high frequency magnetic field are derived from the observations of the 2nd and 3rd harmonics. Both terms decrease abruptly as the temperature deviates from the Curie temperature. It is a very remarkable result that the 2nd harmonic signal is observed above the Curie temperature in contradiction to the simple theoretical consideration. As for the 3rd harmonic its temperature dependence is explained qualitatively by the molecular field theory.
27 citations
TL;DR: In this paper, the ESR signal of Cr 3+ ions in triglycine-sulphate was observed and it was found that a pair of lines gradually approach to each other with increasing temperature in the ferroelectric phase and converge at the Curie temperature.
Abstract: We observed the ESR signal of Cr 3+ ions in triglycine-sulphate. It is found that a pair of lines gradually approach to each other with increasing temperature in the ferroelectric phase and converge at the Curie temperature. The results are interpreted by using the concept of motional narrowing on the basis of the model of order-disorder type. The linewidth for the applied magnetic field nearly parallel to the principal axis z shows an anomalous increase near the Curie temperature. The critical exponent of the linewidth in the ferroelectric region is determined to be 0.5 in the vicinity of the Curie temperature and to be 2.0 far from the Curie temperature.
TL;DR: The new compound manganese gallium germanide has recently been shown to be a uniaxial ferromagnet with a Curie temperature of 185°C as discussed by the authors.
Abstract: The new compound manganese gallium germanide has recently been shown to be a uniaxial ferromagnet with a Curie temperature of 185°C. The easy axis of magnetization coincides with the tetragonal crystallographic c axis. Nearly completely c‐axis‐oriented films with hysteresis loops showing essentially 100% remanence normal to the film plane have been prepared by sputtering. The Curie temperature depends on the film composition. Curie temperatures as low as 110°C have been observed in nonstoichiometric films. These films have a room‐temperature coercivity of 950 Oe compared to ≥2000 Oe for stoichiometric films. At a wavelength of 6328 A the absorption coefficient α (corrected for reflectivity) is 5.8×105 cm−1 and the room‐temperature polar Faraday rotation F is 80 000°/cm. The reflectivity R at normal incidence is 0.47. MnGaGe undergoes no phase changes before melting peritectically at 616°C and the films are stable to oxidation at temperatures well above the Curie point. The low Curie temperature combined w...
TL;DR: The magnetic susceptibility of various BETA -rhombohedral boron samples was measured between 4 and 1300 deg K as mentioned in this paper, with an unusual paramagnetic component, with an experimental number of centers dependent on the temperature of the form N= 2 N/ sub o/ exp {- DELTA E/kT}, ig observed above 500 deg K.
Abstract: The magnetic susceptibility of various BETA -rhombohedral boron samples was measured between 4 and 1300 deg K An unusual paramagnetic component, with an experimental number of centers dependent on the temperature of the form N= 2 N/ sub o/ exp {- DELTA E/kT}, ig observed above 500 deg K The obtained experimental values are: DELTA E approximately 041 BV, N/sub O/ approximately 10 X 10/ sup 22/ Cm/sup -3/ DELTA E is assumed to be the consequence of a gap of about 082 eV between two narrow bands which do not seem to contribute to the conductivity at least for high temperatures (T> 500 deg K) Moreover, a second contribution is observed increasing linearly above 300 deg K with rising temperature and becoming less diamagnetic The slope of the second signal versus temperature is 28 x 10/sup -11/ cm/sup 3/ g/sup -1/ deg/sup -1/ A Curie paramagnetic contribution appears below 77 deg K, which can be accounted for by a part (5 ppM) of the residual impurities (29 references) (auth)
TL;DR: In this article, the influence of the cation distribution on the tetrahedral and octahedral sites upon the Curie temperature in some ferrites has been studied and the migration of ions between the two crystallographic positions is proved by saturation magnetization measurements.
TL;DR: In this article, susceptibility measurements in magnetic fields up to 40 kG between 4 and 300 K on nickel disulphide samples in the composition range NiS1.91-NiS2.09 show that stoichiometric NiS 2.00 is a Curie-Weiss paramagnetic substance.
Abstract: Susceptibility measurements in magnetic fields up to 40 kG between 4 and 300 K on nickel disulphide samples in the composition range NiS1.91-NiS2.09 show that stoichiometric NiS2.00 is a Curie-Weiss paramagnetic substance. A sharp magnetic transition occurs at 31 K on samples which lie below stoichiometry. Below this temperature a low magnetic moment (
TL;DR: In this article, the magnetic susceptibilities of RCu/sub 6/ compounds (R = rare earth) were measured over the temperature range 80 to 12O 0 deg K. The contributions to the magnetic susceptibility were the Curie-Weiss term, expressing the paramagnetism of the localized felectrons and a temperature-independent term for which all the contributions have been estimated.
Abstract: The magnetic susceptibilities of RCu/sub 6/ compounds (R = rare earth) were measured over the temperature range 80 to 12O0 deg K. The contributions to the magnetic susceptibility were the Curie-Weiss term, expressing the paramagnetism of the localized felectrons and a temperature-independent term for which all the contributions have been estimated. The most important contribution to the temperature-independent term is given by an enhanced Pauli paramagnetism. An expression is proposed for calculating the enhancement factors of the Pauli paramagnetism. The anomalous behavior of the SmCu/sub 6/ compound results mainly from Van Vleck-type paramagnetism, and could adequately be calculated on the basis of free Sm/sup 3+/ ions, as in the case of the compound SmAl/sub 3/ (de Wijn, van Diepen and Buschow 1967). (auth)
TL;DR: In this paper, the authors measured the magnetic moments, Curie and compensation temperatures for DyFe 3−x Co x and HoFe 3 −x Co X compounds and explained the variation of transition metal moment on the basis of the rigid band model.
TL;DR: In this article, the magnetic field of type-II superconductors with small magnetization is calculated by minimizing the free energy, and the strange field distribution obtained by Delrieu is confirmed.
TL;DR: In this paper, a new compound of the composition UPTe, belonging to the UXY group compounds (X = pnigogen, Y = chalcogen) has been obtained.
Abstract: A new compound of the composition UPTe, belonging to the UXY group compounds (X = pnigogen, Y = chalcogen) has been obtained. It is assigned to the crystalline structure of the type UGeTe (space group 14/mmm-D). Magnetic investigations performed on single-crystal and powder specimens in the temperature range 4.2 to 1000 K show that it constitutes an uniaxial ferromagnet with a Curie temperature of 85 K. In the measured paramagnetic range the dependence χ = f(T) deviates from the Curie-Weiss law, which is explained by a strong crystal field.
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TL;DR: In this article, the superconducting critical temperature Tc and critical field Hc of Zn Cr and Zn Mn alloys were measured down to 0037°K and the variation of Tc with increasing concentration depends strongly on Tcp/θ, with θ a characteristic temperature, while effects of Hc are similar to previously studied alloys.
TL;DR: In this paper, the low-field magnetic susceptibility of (CH 3 NH 3 ) 2 FeCl 4 was analyzed in terms of critical point behavior, and the critical point exponents, γ and γ′, clearly indicate that the system approximates a two-dimensional Ising antiferromagnet.
TL;DR: Magnetic susceptibilities of the compounds EuχYb1−χB6 have been measured by the Faraday method over the range 1.7-300 K.
TL;DR: Magnetization measurements on TbAl 2 single crystals are reported for 4.2 K in magnetic fields up to 50 kOe applied in the three symmetry directions as discussed by the authors. But no quenching of the magnetic moment is observed.
TL;DR: In this article, simultaneous measurements of magnetization and resistivity of a ferromagnetic CoS 2 near the critical temperature have shown that the negative divergence of d ρ d T occurs exactly at the Curie temperature of 115.9 K.
TL;DR: In this article, the static magnetization of PuAs was measured and it was found to be ferromagnetic with a Curie temperature of 129 K. The saturation moment is 035 μb and the effective paramagnetic moment deduced from the Curie-Weiss law is 097 μb.
TL;DR: In this article, an alternative interpretation of the thermoelectric data of Tang, Craig, and Kitchens is presented, based on the work of the authors of this paper.
Abstract: An alternative interpretation is offered of the thermoelectric data of Tang, Craig, and Kitchens.