Showing papers on "Curie–Weiss law published in 1968"
TL;DR: In this paper, the spin wave contribution to low temperature magnetization is considered in the limits of strong and very weak ferromagnetism, and a simple equation for the magnetic isotherms is obtained in this limit and shown to be valid over a wide temperature range.
Abstract: Calculations are given for the dependence on temperature and magnetic field strength H of the magnetization M of ferromagnetic metals treated on the basis of the itinerant electron model. The spin wave contribution to the low temperature magnetization is considered in the limits of strong and very weak ferromagnetism. For the first limit, problems related to the well-known divergence of the zero field differential susceptibility are briefly discussed. The main part of the paper is concerned with the single particle contributions to the magnetization and associated differential susceptibility for very weak ferromagnetism. A simple equation for the magnetic isotherms is obtained in this limit and shown to be valid over a wide temperature range including 0 °K and the Curie temperature. This equation implies that plots of M 2 against H / M at various temperatures in this range give a series of parallel straight lines. Recently measured isotherms for the material ZrZn 2 are analysed on the basis of the theory, and several characteristic properties of this material are obtained from the analysis.
188 citations
TL;DR: In this paper, the spontaneous magnetization σ and the Curie constant Cmol were measured on a synthetic crystal of CoS2 and they were compatible when they assume Co is in divalent and low-spin state.
Abstract: Magnetic properties of FeS2 and CoS2 having pyrites structure are studied. Magnetic susceptibility of a good natural pyrites (FeS2) crystal is almost temperature‐independent down to 4.2°K. The constant susceptibility is explained by the Van Vleck paramagnetic term and diamagnetic one of the core. This suggests iron in pyrites is in divalent and low‐spin state contrary to the assumption of L. R. Walker et al. that iron in pyrites is in a trivalent state from the Mossbauer isomer‐shift data. CoS2 is a ferromagnet of a Curie temperature of 130°K. The spontaneous magnetization σ and the Curie constant Cmol are measured on a synthetic crystal of CoS2. We obtained the values, σ=44.4 emu/g and Cmol=0.37 emu·deg. The values are compatible when we assume Co is in divalent and low‐spin state. This fact accords with the result of magnetic measurement of FeS2.
69 citations
TL;DR: In this paper, the authors measure the intrinsic nature of resistive transtions as a function of mean free path by making very small mean-free-path films, and they estimate the smearing of the transition near zero resistance.
Abstract: By making very small mean-free-path films we have been able to measure the intrinsic nature of resistive transtions as a function of mean free path. Analysis based on the concepts of Anderson and Josephson leads to an estimate of the smearing of the transition near zero resistance.
56 citations
TL;DR: In this article, the magnetic properties of PrAl2 and ErAl2 have been investigated by neutron-diffraction and susceptibility measurements on powder samples of the above compounds; the results show that the spontaneous mag...
Abstract: The magnetic properties of PrAl2 and ErAl2 have been investigated by neutron‐diffraction and susceptibility measurements on powder samples of the above compounds. The susceptibility data show that both compounds obey the Curie‐Weiss law; the effective moment per molecule in the paramagnetic region is 3.5±0.05 μB for PrAl2 and 9.2±0.1 μB for ErAl2. The neutron‐diffraction measurements confirm that these compounds are ferromagnetically ordered below a Curie temperature of 34°K for PrAl2 and 14°K for ErAl2; the respective saturated ordered moments at the rare earth atom sites are 2.94±0.05 μB and 8.3±0.3 μB. The magnetic form factor data from the ErAl2 coherent magnetic reflections are in good agreement with similar data obtained by other investigators on an Er single crystal. The magnetic scattering intensity of the (111) reflection from PrAl2 was measured just below the Curie temperature TC in order to determine the long‐range magnetic‐order temperature dependence. The results show that the spontaneous mag...
46 citations
TL;DR: The magnetic properties of hexagonal CeAl3 and orthorhombic CeAl4 between 2.2 and 300°K are reported and discussed in detail in this paper, where it is attributed to a combination of crystal field and exchange interactions.
46 citations
IBM1
TL;DR: The specific heat of EuS near the critical point is a homogeneous function of field and temperature as mentioned in this paper, where the specific heat is defined as a function of the temperature and field variation.
Abstract: The specific heat of EuS near the critical point is a homogeneous function of field and temperature. In zero field $\ensuremath{\alpha}=0$ and ${\ensuremath{\alpha}}^{\ensuremath{'}}=\ensuremath{-}0.25$, and along the critical isotherm the field variation is logarithmic.
43 citations
TL;DR: The susceptibilities and lattice parameters for a series of praseodymium hydrides represented by the formula PrHx in which x varies from 0.99 to 2.57 are reported in this article.
Abstract: The susceptibilities (χ) and lattice parameters are reported for a series of praseodymium hydrides represented by the formula PrHx in which x varies from 0.99 to 2.57. χ was measured from 4° to 300° and at field strengths up to 21 kOe. The samples are two‐phase for x ≤ 1.85. Curie–Weiss behavior is observed for all samples above 100°K with slopes in fairly good agreement with that expected for an assemblage of free tripositive ions. Deviations occur below 100°K. These are two kinds—negative for x 2.1. The deviations in the first case are small and appear to result from the crystal‐field interaction. The positive deviations are ascribed to a change of valence for Pr from 3 + to 4 +. Magnetic, electrical, and crystallographic evidence is in accord with this postulate. There is no indication of magnetic ordering in the hydrides at 4.2°K.
36 citations
TL;DR: The pseudobinary systems Y(MnxFe1−x)2 and Y6mn23 show complete solid solubility as mentioned in this paper, and the Curie temperature and the magnetization are lowered by the addition of Mn to YFe2 and by adding Fe to Y6Mn23.
Abstract: The pseudobinary systems Y(MnxFe1−x)2 and Y6(MnxFe1−x)23 show complete solid solubility. The magnetization and the susceptibility from 80° to 1500°K have been measured.The Curie temperature and the magnetization are lowered by the addition of Mn to YFe2 and Y6Fe23 and also by the addition of Fe to Y6Mn23. No magnetic ordering above 90°K is observed for Y(MnxFe1−x)2, if x>0.6 and for Y6(MnxFe1−x)23, if 0.4
32 citations
28 citations
24 citations
TL;DR: In this article, a weak ferromagnet with a remanence and a canting angle of the expected size is measured and the macroscopic moment has an anomalous behaviour close to the Curie temperature.
TL;DR: In this paper, the intrinsic spin-wave linewidth was measured up to temperatures within a few degrees of the Curie temperature, where the authors showed that at low temperatures, up to 30°K, the ferromagnetic relaxation appears to result from two-magnon coupling of the k=0 mode to modes of higher k, which relax by the three-magon confluence process.
Abstract: The rather simple magnetic structure of the ferromagnetic insulator CdCr2Se4 makes it an attractive substance for the study of magnetic relaxation mechanisms in general, but in particular those mechanisms of importance in the vicinity of the ordering temperature. The ferromagnetic relaxation has been studied here by means of both FMR and high‐power parallel‐pump techniques. Using the latter technique, the intrinsic spin‐wave linewidth was measured up to temperatures within a few degrees of the Curie temperature. Near the Curie temperature the linewidth diverges as (T0‐T)−1 with T0=133°K. This value of T0 is in close agreement with our measured value of the Curie temperature 130°K. At low temperatures, up to 30°K, the relaxation appears to result from two‐magnon coupling of the k=0 mode to modes of higher k, which relax by the three‐magnon confluence process.
TL;DR: In this article, the magnetic and thermal properties of a certain kind of plane deco- rated Ising lattice were investigated. But the authors focused on the temperature and magnetic field dependence of the magnetization, the susceptibility and the heat capacity.
Abstract: We discuss in detail the magnetic and thermal properties of a certain kind of plane deco rated Ising lattice; that is, its interesting spin-ordering characteristics, such as the temperature and magnetic field dependence of the magnetization, the susceptibility and the heat capacity are investigated. These characteristics may be classified according to the ratio between two kinds of exchange coupling parameters. The system shows metamagnetism in certain cases. The characteristic magnetic field at which a logarithmic singularity takes place in the suscepti bility as well as the heat capacity is obtained as a function of temperature. In some cases two chracteristic fields are found below a certain temperature, above which only the one characteristic field survives up to a higher temperature. A number of typical curves which represent the relations of the magnetization, the magnetic susceptibility and the heat capacity with the magnetic field at a fixed temperature and with temperature at a fixed strength of magnetic field are investigated.
TL;DR: The temperature coefficient of resistivity has been determined for several FePd alloys near the Curie temperature and has been found to show a sharp peak at the curie point.
TL;DR: Giant moment inducement by Fe dissolved in Ni 3 Ga has been observed in alloys with composition Ni 75− x Ga 25 Fe x with x = 0.05, 0.1,0.2 and 1.0 as mentioned in this paper.
TL;DR: In this article, measurements of magnetization at temperatures down to 4°K and in applied fields up to 20 koe have been made on the cubic Laves phase compounds (Zr1-x Ti x )Zn2 for values of x ranging from 0 to 0·26.
Abstract: Measurements of magnetization at temperatures down to 4°K and in applied fields up to 20 koe have been made on the cubic Laves phase compounds (Zr1-x Ti x )Zn2 for values of x ranging from 0 to 0·26. Lattice parameters have also been measured. The magnetization and Curie temperature of the system increase with decreasing lattice parameter.
TL;DR: In this paper, the magnetostriction of an antiferromagnet Au 2 Mn of the screw type spin arrangement was measured up to a magnetic field intensity of 80 kOe in the temperature range from room temperature to the liquid He point.
Abstract: The magnetostriction of an antiferromagnet Au 2 Mn of the screw type spin arrangement was measured up to a magnetic field intensity of 80 kOe in the temperature range from room temperature to the liquid He point. Both the longitudinal and transverse magnetostriction curves consist in series of (1) a fairly complicated part in a low magnetic field range, (2) a contraction of the order of 200×10 -6 , and (3) a weak contraction proportional to the intensity of the magnetic field in a high field range. At temperatures above 200°K, slight expansion can be seen between the stages (2) and (3) in the case of the longitudinal effect. The observed magnetostrictions can be considered to be caused by (1) the rotation of the magnetic moment in the c -plane, (2) the rotation of the magnetic moment toward the c -axis, and (3) the change in screw angle during the course of magnetization.
TL;DR: Magnetic measurements in applied fields up to 16 kOe and at temperatures down to 4.2°K have been made on the cubic Laves phase compounds (Zr 1− x Hf x ) Zn 2 for 0 ⩽ x ⩾ 0.16 as discussed by the authors.
TL;DR: In this paper, a decoupling scheme for the Green function appearing in the theory of the spin-heisenberg ferromagnet was introduced, where the magnetization has no spurious term in T3 and the coefficient of the term is within a few percent of the Dyson exact result.
Abstract: A new first-order decoupling scheme for the Green function appearing in the theory of the spin- Heisenberg ferromagnet is introduced. At low temperatures the magnetization has no spurious term in T3 and the coefficient of the term in T4 is within a few percent of the Dyson exact result. The Curie temperature is equal to the random phase approximation Curie temperature.
TL;DR: In this paper, the experimental and theoretical concept concerning the magnetic properties of 2-dimensional arrangements of small particles with different strengths of interaction is discussed, taking into account recent results on isolated small single-domain particles, a representation for a whole scale of possible structures from these to closely packed ferromagnetic films is given, using a molecular field formalism.
Abstract: The experimental and theoretical concept concerning the magnetic properties of 2-dimensional arrangements of small particles with different strengths of interaction is discussed. Taking into account recent results on isolated small single-domain particles, a representation for a whole scale of possible structures from these to closely packed ferromagnetic films is given, using a molecular field formalism. The interaction considered may be much weaker than the full ferromagnetic exchange coupling. The resultant collective magnetization M of such aggregates of small particles may be considerably lower than their spontaneous magnetization M s . A transition temperature T A towards occurrence of superparamag-netism may appear that is well below the Curie temperature Θ of the individual particles. These effects seem to be consistent with experimental data obtained by a number of authors using various methods of measurement. Observations of time effects at magnetization reversals in very thin films also support the aforementioned model.
TL;DR: An expression for the electric field dependence of the phonon density of states and the Curie temperature of a ferroelectric in its paraelectric state using double time Green function technique was obtained in this article.
TL;DR: In this article, it was shown that if temperature increases from below the Curie point (Tc = 3 5 6. 6 °C) the magnetic structure of the material changes from the ferromagnetic state to a system of single domain or superparamagnetic particles, which are relatively stable in the paramagnetic region just above Curie temperature.
Abstract: Measurements of non equilibrium critical magnetic properties of 9 9 . 9 9 8 % nickel between 3 4 8 and 3 6 0 °C lead to the following conclusion: If temperature increases from below the Curie point (Tc = 3 5 6 . 6 °C) the magnetic structure of the material changes from the ferromagnetic state to a system of single domain or superparamagnetic particles, which are relatively stable in the paramagnetic region just above Curie temperature. Remanence, coercivity and after effect show typical behaviour of small ferromagnetic particles. The critical exponents in the ferromagnetic region are 0 . 4 3 9 and 0 . 4 6 2 for remanence and coercivity respectively.
TL;DR: In this article, it was shown that spin impurities in ferromagnets may produce an anomalously large polarization of their environment at temperatures slightly above the Curie temperature, which is known as the anomalous large polarization.
TL;DR: In this article, the magnetic susceptibilities of the system UO 2+x · y ThO 2 have been investigated with respect to the average uranium valency (or x) as well as the atomic ratio /(U+Th) (or y).