Showing papers on "Ferrimagnetism published in 1977"
TL;DR: In this article, the magnetic properties of a triangular Ising lattice with antiferromagnetic nearest neighbor interaction and ferromagnetic second neighbor interaction were investigated at finite-temperature.
Abstract: Molecular field approximation is applied to a triangular Ising lattice with antiferromagnetic nearest neighbor interaction J and ferromagnetic second neighbor interaction J ' to study the magnetic behavior at finite temperatures. In the range of 0> J '/ J >-0.8, with increasing temperature the system is found to have a second-order transition from a ferrimagnetic state to an antiferromagnetic state in which one of three sublattices is completely disordered. Another second-order transition occurs in the ferrimagnetic state. Magnetic structure factor, free energy, magnetic specific heat, differential magnetic susceptibility as well as sub-lattice magnetization are calculated numerically with parameter J '/ J . Critical magnetic field of first-order transition from antiferromagnetic state to ferrimagnetic state is also evaluated. Discussion is given in connection with magnetic ordering in CsCoCl 3 and CsCoBr 3 .
247 citations
TL;DR: Magnetic and neutron diffraction experiments have been performed on a single crystal of the layered compound BaCo 2 (AsO 4 ) 2, and the cobalt moments lie in a plane ( X - Y model) and order abruptly at T c = 5.4 K with a helical structure.
Abstract: Magnetic and neutron diffraction experiments have been performed on a single crystal of the layered compound BaCo 2 (AsO 4 ) 2 . The cobalt moments lie in a plane ( X - Y model) and order abruptly at T c = 5.4 K with a helical structure. An in-plane applied field induces a quite original 2D “ferrimagnetic” structure. At lower temperature the transition becomes irreversible and this structure remains in zero field.
46 citations
TL;DR: In this article, measurements at 1.4 K on single crystal CoNb2O6 (TN = 2.95K) showed that the AFM sublattices are canted 34° from the c axis in the a-c plane, and are not collinear along the a axis as had been inferred from neutron diffraction data.
34 citations
IBM1
TL;DR: In this paper, the spontaneous Hall effect and magnetization of a series of rare earth-transition metal amorphous film alloys fit a model that the Hall asymmetric scattering is simply the sum of the Hall angles of the alloy components.
Abstract: Measurements of the spontaneous Hall effect and magnetization of a series of rare earth-transition metal amorphous film alloys fit a model that the Hall asymmetric scattering is simply the sum of the Hall angles of the alloy components. Alloys of the form Gd .2 (TM) .8 where TM is Mn, Fe, Co or Ni show a maximum of \rho_{H}/\rho the Hall angle, (where ρ H is the Hall resistivity and ρ the sample resistivity) for Gd .2 (TM) .8 of 6%. We find that other rare earth elements have lower \rho_{H}/\rho ratios than Gd and that Nd-Fe alloys exhibit a smaller \rho_{H}/\rho than Gd-Fe because the Nd moments are in an disordered state. Of the alloys studied Gd .2 (TM) .8 is suitable for a Hall sensor because R s the spontaneous Hall coefficient ( \rho_{H} = R_{s}4\piM ) is also large, approximately 10-2μΩcm/G. This is because Gd .2 Fe .8 is a nearly compensated ferrimagnet and 4\piM is low. The anisotropic magnetoresistance in rare earth-transition metal alloys is about 0.1 to 0.2% and does not scale with ρ. The Corbino disc type magnetoresistance is found to be smaller than expected because in the demagnetized state magnetic domains remain effective Hall scatterers.
25 citations
TL;DR: The origin of the spontaneous magnetization of Cu 2 SeO 4 is considered to be a collinear ferrimagnetic arrangement of the Cu 2+ moments on two different sites as mentioned in this paper.
Abstract: Cu 2 SeO 4 shows spontaneous magnetization below 58.8 K. Its origin is considered to be a collinear ferrimagnetic arrangement of Cu 2+ moments on two different sites.
25 citations
TL;DR: The magnetic properties of actinide Laves compounds (cubic C-15 crystal structure) with iron were studied by magnetization, neutron diffraction, and Moessbauer effect techniques.
Abstract: The magnetic properties of the actinide Laves compounds (cubic C-15 crystal structure) with iron were studied by magnetization, neutron diffraction, and Moessbauer-effect techniques. All the compounds exhibit a spontaneous magnetization. Magnetic moments of 0.06, 1.09, 0.45, and -0.4..mu../sub B/ are associated with the U, Np, Pu, and Am ions, respectively. The corresponding iron moments are 0.6, 1.4, 1.5, and 1.7..mu../sub B/. The ferrimagnetic nature of AmFe/sub 2/ suggests a partial occupancy of the Am/sup 2 +/:f/sup 7/ state, inasmuch as the Am/sup 3 +/:f/sup 6/ state has a nonmagnetic ground state.
24 citations
TL;DR: In this paper, a magnetic phase diagram of the Fe 2-X Mn x As system is proposed and discussed qualitatively on the basis of the molecular field theory, which is a first order phase transition between the ferrimagnetic state of the Mn 2 Sb type and the antiferromagnetic spin structures of Fe 2 As type.
Abstract: Magnetic and crystallographic measurements on Fe 2.1- x Mn x As with 0≦ x ≦2.1 are made in the temperature range between 77 and 600 K. The compounds with 0≦ x <1.29 and 1.52< x ≦2.1 have the antiferromagnetic spin structures of the Fe 2 As and Mn 2 As types, respectively. The compounds with 1.29≦ x ≦1.52 show a first order phase transition between the ferrimagnetic state of the Mn 2 Sb type and the antiferromagnetic state of the Fe 2 As type. A magnetic phase diagram of Fe 2- x Mn x As system is proposed and discussed qualitatively on the basis of the molecular field theory.
23 citations
TL;DR: In the ZnxMn2−xSb system, the tetragonal, anti-PbFCl structure occurs between Mn2Sb and ZnMnSb as discussed by the authors.
20 citations
TL;DR: In this article, a fundamental law that relates the hysteresis losses to the magneti~ation state is generalized to Ni ferrite and to mixed NiZn and NiCd ferrites.
Abstract: A fundamental law previously found in YIG, which relates the hysteresis losses to the magneti~ation state is generalized to Ni ferrite and to mixed NiZn and NiCd ferrites. The interpretation which is given is based on the domain wallsize theory previously proposed by Globus : the energy lost by the continuous pinning and depinning of the domain wall as it moves and the energy lost by the formation and the destruction of a part of the domain wall surface may be the origins of the losses which find their expression in the hysteresis loop. That results in an experimental method to determine, from simple measurements of loop areas on polycrystalline samples, the domain wall energy y and the exchange constant A.
18 citations
TL;DR: In this article, it was shown that a temperature dependent number of the ferric ions does not participate in the ferrimagnetism of those compounds with compositiony ≥ 0.4.
Abstract: Static magnetization measurements on the ferrimagnetic spinels Fe2(1−y)Mg1+y
Ti
y
O4 withy=0.3, 0.4, 0.5, and 0.6 show that these compounds have no well-defined orderdisorder transition temperature and that their ferrimagnetism may not be described in terms of the Neel theory. From the Mossbauer spectra we conclude that a temperature dependent number of the ferric ions does not participate in the ferrimagnetism of those compounds with compositiony≧0.4. The explanation of the observed magnetic and Mossbauer properties is based on the assumption that each ferric ion must have at least two magnetic linkages of the type Fe
A
3+
−O2−−Fe
B
3+
in order to couple its magnetic moment to the neighbouring ones over the entire temperature interval between 0 K and the respective Neel temperature.
17 citations
TL;DR: In this paper, the authors presented the achievement of a work upon the magnetization mechanisms based on the concept of the total anisotropy K and on a model for hysteresis loop previously proposed.
Abstract: The author presents the achievement of a work upon the magnetization mechanisms based on the concept of the total anisotropy K and on a model for hysteresis loop previously proposed. Initial magnetization curves of ferrites and YIG are reduced to a universal curve as a function of K and of the mean grain size of the sample. The same procedure allows the author to obtain a universal hysteresis loop.
TL;DR: Magnetization and susceptibility measurements were made on polycrystalline samples of Zn 1- x Ni x Cr 2 S 4 from 4.2 K to 800 K in magnetic fields up to 16.5 kOe.
Abstract: Magnetization and susceptibility measurements were made on polycrystalline samples of Zn 1- x Ni x Cr 2 S 4 from 4.2 K to 800 K in magnetic fields up to 16.5 kOe. The inverse susceptibilities except for ZnCr 2 S 4 show a non-linear behavior characteristic of a ferrimagnet. This indicates that the system has a magnetic moment on Ni 2+ in contrast with NiRh 2 S 4 and the sign of Ni 2+ –Cr 3+ exchange interaction is negative. The saturation magnetization of the sample (x=0.40) is equal to 3.0±0.1 µ B /molecule at 4.2 K. Electrical resistivity of the sample (x=0.40) was measured between 77 K and 300 K, and it is semiconducting (3×10 3 \(\varOmega\) cm at R. T.).
TL;DR: In this article, the magnetic structures of three compounds belonging to the series [ACu3]-B4)O12 were determined by neutron diffraction powder data, and they were classified as ferrimagnetic and antiferromagnetic, respectively.
Abstract: The magnetic structures as determined by neutron diffraction powder data of three compounds belonging to the series [ACu3](B4)O12 are described. ThCu3Mn4O12 is ferrimagnetic (Tc = 430 K), Ca(Cu0.78Mn0.22)3Mn4O12 ferromagnetic (Tc = 350 K), while CaCu3Ti4O12 is antiferromagnetic (TN = 27 K).
Patent•
07 Jan 1977TL;DR: In this paper, the authors proposed a method for the manufacture of glass-ceramic articles having integral surface layers exhibiting ferrimagnetic behavior, which can be used for the recording, storage, and erasing of information.
Abstract: This invention relates to the manufacture of glass-ceramic articles having integral surface layers exhibiting ferrimagnetic behavior. More specifically, this invention is directed to glass bodies having compositions within the Li 2 O-Al 2 O 3 -Fe 2 O 3 -SiO 2 -TiO 2 base system, and that additionally contain NiO and/or CoO, which, when heat treated under oxidizing conditions to effect crystallization in situ to glass-ceramic articles, spontaneously develop crystallites of NiFe 2 O 4 and/or CoFe 2 O 4 in the surfaces thereof. The ferrite surfaces can be magnetized in a strong magnetic field and demonstrate magnetic properties eminently suitable for the recording, storage, and erasing of information.
TL;DR: In this article, the effect of thermal annealing and the contact printing method by Curie point writing for visual display of magnetic information recorded on magnetic tapes or discs is described.
Abstract: Ferrimagnetic amorphous Tb-Fe films prepared by rf sputtering or thermal evaporation have a perpendicular anisotropy, a low Curie point (Tc) and large values of coercivity (Hc) over a wide range of temperature. This paper describes the effect of thermal annealing and the contact printing method by Curie point writing for visual display of magnetic information recorded on magnetic tapes or discs. The values of Hc, Tc and the room temperature magnetization (Ms) are reduced by thermal annealing. Thermomagnetic contact printing in an amorphous Tb-Fe film has been tried. It is accomplished by putting the film on the recorded magnetic tape or disc and then heating up the film by photoflash light. The information is observed by means of the polar Kerr effect. In this printing method high resolution printing is realized and analog printing is possible.
TL;DR: In this article, the magnetisation and axial anisotropy of thulium have been measured with a vibrating sample magnetometer in the paramagnetic, the ferromagnetic and the c axis modulated and the ferrimagnetic antiphase domain structures.
Abstract: The magnetisation and the axial anisotropy of thulium have been measured with a vibrating sample magnetometer in the paramagnetic, the ferromagnetic, the c axis modulated and the ferrimagnetic antiphase domain structures. A mean field model which takes full account of the strong crystal field is described and the calculations are compared with experiment.
TL;DR: In this article, a high power Ku-band W.G. junction circulator was developed for radar applications, in both E and H plane configurations by careful choice of the ferrimagnetic material loading the junction to avoid excitation of higher order spin wave modes and to minimise the absorption loss in the material.
Abstract: High power Ku-band W.G. junction circulators have been developed for radar applications, in both E and H plane configurations by careful choice of the ferrimagnetic material loading the junction to avoid excitation of higher order spin wave modes and to minimise the absorption loss in the material. From the constraints imposed on the choice of material, it is necessary to characterise the basic junction accurately to achieve the circulator performance over the required radar bandwidth, and results of this work are presented. The performance of the units broadbanded by means of quarter wave impedance steps in the waveguide demonstrates the usefulness of the approach with peak power levels at frequencies in the 16 to 17 GHz band as high as 15OKW in the E-plane configuration and average power up to 300 watts in the H-plane configuration, with bandwidths of 5% andlO% respectively.
TL;DR: The donor acceptor compounds TTF-MS4C4(CF3)4 where TTF = tetrahiafulvalene and M = Cu, Au, Pt, Ni are mixed-stack quasi-one-dimensional magnetic insulators of remarkable variety as discussed by the authors.
Abstract: The donor-acceptor compounds TTF-MS4C4(CF3)4 where TTF = tetrahiafulvalene and M = Cu, Au, Pt, Ni are mixed-stack quasi-one-dimensional magnetic insulators of remarkable variety. For M = Cu, Au, a novel progressive spin-lattice dimerization occurs (spin-Peierls transition). For M = Pt, Ni, ferro/ferrimagnetic chains develop with moderate/weak antiferromagnetic coupling.
TL;DR: The magnetic properties of the fluoride K5V3F14 of the chiolite type have been investigated on single crystals as mentioned in this paper, and the expected ferrimagnetic behaviour has been pointed out, the ordering temperature being 18 ± 1 K.
TL;DR: In this article, the transition from the ferrimagnetic state (FeCr 2 S 4 ) to the AF states (FeIn 2S 4 at low temperature) occurs in a relatively broad range of composition and the solid solutions FeCr 2−x In x S 4 remain spinel type for all x.
Abstract: The solid solutions FeCr 2− x In x S 4 remain spinel type for all x . Fe is moved towards B sites when x is increaces. It is shown that the transition from the ferrimagnetic state (FeCr 2 S 4 ) to the AF state (FeIn 2 S 4 at low temperature) occurs in a relatively broad range of composition.
IBM1
TL;DR: In this paper, the temperature dependence of the extraordinary Hall resistivity and the ordinary resistivity of amorphous Co-Gd-Mo-Ar thin films have been investigated from 4.2°K to the ferrimagnetic Curie temperature; the nominal composition of these films was Co65Gd10Mo15Ar10.
Abstract: The temperature dependence of the extraordinary Hall resistivity and the ordinary resistivity of amorphous Co-Gd-Mo-Ar thin films have been investigated from 4.2°K to the ferrimagnetic Curie temperature; the nominal composition of these films was Co65Gd10Mo15Ar10. The extraordinary Hall resistivity reverses sign at the compensation temperature and reflects the paramagnetic susceptibility above the Curie temperature. The temperature dependence of the Hall resistivity can be adequately expressed as R1(Co)MCo + R1(Gd)MGd, where MCo, and MGd are the subnetwork magnetizations determined from a mean field fitting procedure. This fit emphasizes the inappropriateness of spin fluctuation scattering models which are relevant to the crystalline phases. Such models predict a minimum in Hall resistivity at low temperatures which is not observed experimentally.
TL;DR: A large hysteresis at the metamagnetic phase transition between the antiferromagnetic (AF) and the ferrimagnetic (Fi) orders is indicated in the Raman spectra of these compounds.
TL;DR: In this paper, a simple model which involves transferred hyperfine fields from the lanthanide and cobalt ions and which allows for crystal field quenching of the holmium moment is presented.
Abstract: The ferrimagnetic system (GdxY1−x)Co2 has been studied by the Mossbauer effect of 155Gd and by the NMR of 165Ho as a substitutional impurity. The data are interpreted in terms of a simple model which involves transferred hyperfine fields from the lanthanide and cobalt ions and which allows for crystal field quenching of the holmium moment.
TL;DR: In this article, the dependence of magnetization on temperature was measured between room temperature and that of liquid helium, with values up to 60.7 kOe. Low temperature results are in most cases ascribed to ferrimagnetic ordering but with canting of ion moments to explain why magnetic saturation has not been attained even with the maximum field applied.
TL;DR: In this article, the Yafet-Kittel effect was used to explain the changes in the magnetic moment at 0 K to 4.60 µB as the temperature increases from 25 to 1 350 °C.
Abstract: Mn-Zn ferrite prepared by wet methods show high reactivity : pressed samples reach almost theoretical density at temperatures lower than those usually required for sintering powders prepared by common ceramic techniques. They also show a largely different cation site occupancy which evolves with temperature approaching that of ceramic ferrites. Mossbauer spectra on MnFe2O4 also prepared by wet methods confirm such evolution which causes the magnetic moment at 0 K to shift from 4.11 to 4.60 µB as the temperature increases from 25 to 1 350 °C. The temperature dependence of magnetization with increasing Zn content for as prepared samples varies in a different way from that of samples annealed at 1 350 °C and quenched in water. The values of magnetic moments lower than those expected by the normal Neel theory of ferrimagnetism are explained rather well by a certain phenomenological evidence of a Yafet-Kittel effect.
01 Jan 1977
01 Jan 1977
TL;DR: The transition temperature from the Yafet-Kittel to the Neel ferrimagnet decreases with x as mentioned in this paper, and vanadium substitutes Cr in B sites in spinel phase up to x = 0.6.
Abstract: The compounds MnCr2−xVxS4 exist in the spinel phase up to x = 0.6. Vanadium substitutes Cr in B sites. V3+ couples antiferromagnetically to Cn3+. The transition temperature from the Yafet-Kittel to the Neel ferrimagnet decreases with x.