Showing papers on "Magnetic anisotropy published in 1985"
TL;DR: In this article, the results of magnetic studies of thin film, periodic, Pd/Co layered structures with ultrathin cobalt (4-13 A) were presented and it was shown that films with Co thicknesses less than 8 A are easy to magnetize along a direction normal to the film surface.
Abstract: This letter presents the results of magnetic studies of thin film, periodic, Pd/Co layered structures with ultrathin cobalt (4–13 A). We show that films with Co thicknesses less than 8 A are easy to magnetize along a direction normal to the film surface. The best films have a saturation magnetization of about 500 emu/cm3 and a coercivity of 550 Oe, and thus they are candidates for a vertical magnetic recording medium. We attribute the perpendicular magnetic easy axis in these films to surface anisotropy at Pd/Co interfaces and strain in thin Co layers.
874 citations
TL;DR: In this article, anisotropic behavior of the magnetization versus magnetic field curves in the basal plane has been observed for Sm2Fe14B, indicating large amplitude of the high order coefficients, K2 and K3.
Abstract: Static magnetic measurements have been carried out on single crystals of Nd2Fe14B, Sm2Fe14B, and Y2Fe14B from 4.2 to 590 K. Values of K1 estimated from high field measurements at room temperature are 4.5, −12, and 1.1 MJ/m3 for Nd2Fe14B, Sm2Fe14B, and Y2Fe14B, respectively. Anisotropic behavior of the magnetization versus magnetic field curves in the basal plane has been observed for Sm2Fe14B, indicating large amplitude of the high order coefficients, K2 and K3. In Nd2Fe14B, the magnetization has been found to tilt from the c axis and simultaneously increase in magnitude. Average Fe moment is estimated to be 2.23 μB/Fe at 4.2 K from the saturation magnetization of Y2Fe14B.
233 citations
TL;DR: In this article, a method for determining magnetic anisotropy using anhysteric remanence susceptibility is described, and the magnetic fabric of a collection of Trenton Limestone specimens has been determined using this method, as well as by conventional anisotropic of magnetic susceptibility.
Abstract: A new method for determining magnetic anisotropy using anhysteric remanence susceptibility is described. The magnetic fabric of a collection of Trenton Limestone specimens has been determined using this method, as well as by conventional anisotropy of magnetic susceptibility. The results demonstrate the usefulness of the new method for finding the magnetic fabric of rock units such as the Trenton in which the bulk magnetic susceptibilities are low. A model is proposed to explain the observed foliated and lineated fabric as a consequence of overburden compaction and regional horizontal stresses. The original fabric is inferred to have been isotropic; the anisotropy resides in secondary magnetite of Late Paleozoic age. It is argued that the observed magnetic fabric must therefore be Alleghenian or younger in age. Our method has the potential to determine paleostress directions in carbonates elsewhere, provided our assumptions are correct.
213 citations
TL;DR: In this article, the magnetic properties of the Nd2(Fe1−xCox)14B system were investigated to improve the thermal properties of Nd•Fe•B magnets.
Abstract: We have investigated the magnetic properties of the Nd2(Fe1−xCox)14B system to improve the thermal properties of the Nd‐Fe‐B magnets. Nd2(Fe1−xCox)14B exists in the tetragonal form in the entire range of 0≤x≤1. In this system, the replacement of Fe by Co significantly increases the Curie temperature. The room‐temperature magnetization of Nd2(Fe1−xCox)14B has its maximum value at x=0.1. However, because of the decrease in the anisotropy energy and the saturation magnetization by further substitution of Co for Fe, a reasonable substitution range of Co is suggested to be x<0.2 in the sintered Nd‐Fe‐B magnet. In this range of Co, we have succeeded in improving the reversible temperature coefficient of the remanence for the Nd‐Fe‐B magnets.
200 citations
TL;DR: In this article, a combination of self-consistent energy band and density functional theory is used to describe the last transition metals in the periodic table and the onset of ferromagnetic ordering and the observed relationship between lattice constant and magnetic moment.
Abstract: Agreement between calculated and measured atomic volumes, bulk moduli and cohesive energies of the light actinide metals establishes the combination of self-consistent energy band and density functional theory as an appropriate description of these, the last, transition metals in the periodic table. Similar calculations for NaCl-type compounds of the light actinides are able to explain characteristic trends in lattice constant and bulk modulus. Furthermore, the onset of ferromagnetic ordering and the observed relationship between lattice constant and magnetic moment are, at least qualitatively, given correctly. Relativistic, in particular spin-orbit, effects alter the calculated magnetic properties dramatically being responsible for both large magnetic anisotropy and predominant orbital moments in all magnetic light actinide compounds in which the f electrons are itinerant. The calculated magnetic moments of NaCl-type uranium compounds are, however, only in agreement with experiment when the pairing energy between electrons includes an orbital contribution.
173 citations
Patent•
14 Oct 1985
TL;DR: In this paper, a photoelectromagnetic recording medium and a magnetic recording medium by implanting ions of a rare-earth element into a 3D transition metal layer, and providing uniaxial magnetic anisotropy.
Abstract: PURPOSE:To obtain a photoelectromagnetic recording medium and a magnetic recording medium by implanting ions of a rare-earth element into a 3d transition metal layer, and providing uniaxial magnetic anisotropy. CONSTITUTION:Ni, Co, Fe, Mn, Cr, etc. or the alloy of said metals can be exemplified as the 3d transition metal. And dysprosium (Dy), terbium (Tb), gadolinium (Gd), europium (Eu), samarium (Sm), praseodymium (Pr), etc. can be exemplified as the rare-earth element. The recording medium is obtained by implanting ions of the rare-earth element into the 3d transistion metal layer while impressing a magnetic field. Namely, ions are generated by an ion source, and the ions are drawn out by the acceleration voltage at 20-30kV. Then the ions are implanted into the specified target, or said metallic layer, by the acceleration voltage at up to about 200kV. Uniaxial magnetic anisotropy in the impressing direction can be provided to the magnetic medium in this way.
168 citations
TL;DR: In the MR magnetic head of the present invention, its sensing element (2) comprises a plurality of superposed magnetic layers (4,5) having magnetoresistance effect in at least one of them and a nonmagnetic intermediate layer (3) sandwiched therebetween, and a sensing current is fed to flow in the sensing element in the same direction as a signal magnetic field applied to the element as discussed by the authors.
Abstract: In the MR magnetic head of the present invention, its sensing element (2) comprises a plurality of superposed magnetic layers (4,5) having magnetoresistance effect in at least one of them and a nonmagnetic intermediate layer (3) sandwiched therebetween, and a sensing current (i) is fed to flow in the sensing element (2) in the same direction as a signal magnetic field applied to the element. Each of the magnetic layers (4,5) is so formed as to have an easy axis of magnetization substantially perpendicular to the signal magnetic field or to have an isotropic magnetic characteristic in the magneticfilm plane, thereby avoiding generation of Barkhausen noise with certainty.
154 citations
TL;DR: In this article, the 3d Fe moment on different sites in Y2Fe14B at 4.2 K is closely related to local environment, and it is reduced to 1.95 μB by 4d−3d electron transfer and hybridization for Fe atoms which have the largest coordinance number of Y atoms.
Abstract: Outstanding permanent magnet properties were recently observed in a Nd‐Fe‐B compound which was shown to crystallize in a new phase, R2Fe14B. Polarized neutron measurements are reported on Y2Fe14B and Nd2Fe14B single crystals. The 3d Fe moment on different sites in Y2Fe14B at 4.2 K is closely related to local environment. Its value is maximum for atoms in σ‐like layers at the center of an Fe antiprism. On the contrary, it is reduced to 1.95 μB by 4d‐3d electron transfer and hybridization for Fe atoms which have the largest coordinance number of Y atoms, 4. The measurements at 250 K reveal a larger thermal decrease of the 3d moment for Fe atoms which exhibit shortest Fe‐Fe interatomic distances. This property reveals a reduction of 3d magnetic interactions for short distances as was previously observed in R2Fe17 compounds. In Nd2Fe14B, the low values obtained at 4.2 K for Nd magnetic moments suggest that the magnetic structure, determined by a competition between 3d‐4f exchange interactions and crystal‐fiel...
152 citations
TL;DR: In this article, the lattice constants of these compounds were determined and the magnetic properties, comprising the temperature dependence of the magnetization in the range 4.2-700 K and the field dependence of magnetization at 4.1-4.2 K in fields up to 35 T.
117 citations
TL;DR: In this paper, the ternary tetragonal structure R2Fe14B has been used for growing permanent magnet materials, where R is one of the rare earth elements.
Abstract: A whole new class of high‐performance permanent magnet materials is based on the ternary tetragonal structure R2Fe14B, where R is one of the rare‐earth elements. We have successfully grown single crystals of this structure with R=Y, Nd, and Tb. Y is a nonmagnetic rare‐earth substitute, while Nd and Tb couple ferro‐ and ferrimagnetically, respectively, relative to the iron moment. All three of the compounds have [001] easy axes at room temperature, although the Nd compound exhibits a spin reorientation away from the [001] below about 150 K. Nd2Fe14B has a saturation induction at room temperature of 16.2 kG, which places an upper limit of approximately 65.6 MGOe on the energy product obtainable by magnets based on that material. While Tb2Fe14B exhibits a smaller magnetization because of ferrimagnetic coupling of the rare earths and the iron, it also has an extremely large magnetic anisotropy which is nearly temperature independent between 4.2 and 300 K.
116 citations
TL;DR: In this article, a polycrystalline garnet with no preferred orientation and no impurity crystalline phase detectable by x-ray analysis was prepared by rf diode sputtering which was followed by annealing for crystallization.
Abstract: Using glass substrates, we have prepared highly Bi‐substituted garnet [(Bi,Y,Fe,Al)8O12 and (Bi,Gd,Fe,Al)8O12] films by rf diode sputtering which was followed by annealing for crystallization. The films were polycrystalline garnet with no preferred orientation and no impurity crystalline phase detectable by x‐ray analysis, which contained 1.1–1.4 Bi ions per formula unit. The films crystallized directly during the sputter deposition when the substrate temperature Ts>440 °C. Film quality was best when Ts was just below 440 °C. The film had magnetic anisotropy perpendicular to the film plane, which is stress induced. In the (Bi,Gd,Fe,Al)8O12 film, the magnetization normal to the film plane exhibited strong coercivity, Hc=600 Oe, and a large remanence‐to‐saturation ratio, Mr/Ms=1, while in the (Bi,Y,Fe,Al)8O12 film, weak Hc (200 Oe) and small Mr/Ms (0.47). These films had large Faraday rotation, typically 1.5×104 deg/cm at λ=633 nm, owing to the high Bi substitution.
TL;DR: In this paper, the authors have prepared Ba-ferrite film disks and evaluated their magnetic read/write characteristics, and the results showed that they have promising potential as a high-density perpendicular magnetic recording medium.
Abstract: The authors have prepared Ba–ferrite film disks and evaluated their magnetic read/write characteristics. The c‐axis‐oriented Ba–ferrite thin films were formed epitaxially on c‐axis‐oriented ZnO films by means of a targets‐facing‐type sputtering system. The direction of easy magnetization in the film with perpendicular crystalline anisotropy is almost perpendicular to the film plane. Thus, the perpendicular remanence is more than 60 times as large as the in‐plane one. The simple Ba–ferrite films, however, have a coercive force, Hc⊥ above 2 kOe which is too large to write on by means of a conventional head. The substitution of In3+ in the Ba–ferrite films makes the Hc⊥ values decrease to about 1 kOe without increasing the critical temperature, Tcritical, of c‐axis orientation. The read/write characteristics of the films were measured with a MnZn–ferrite ring head. The reproduced signal exhibits clear dipulsive waveforms as the dipulse ratio exceeds 0.7. Furthermore, the overwrite ratio decreases below −28 dB for the In3+‐substituted Ba‐ferrite film disk. The Ba–ferrite film disks have promising potential as a high‐density perpendicular magnetic recording medium.
TL;DR: In this paper, the first self-consistent spin-polarized band structure calculation of the ferromagnetic compound MnBi in its low-temperature phase has been performed, treating the spin-orbit interaction as a perturbation using scalar-relativistic wavefunctions.
Abstract: The first self-consistent spin-polarised band-structure calculation of the ferromagnetic compound MnBi in its low-temperature phase has been performed. The spin-orbit interaction was treated as a perturbation using scalar-relativistic wavefunctions. On the Mn atoms an effective 3d5.5 configuration is found, with a magnetic moment of 3.6 mu B. A part of the d electrons is rather delocalised and strongly hybridised with Bi 6p states. This leads to a low density of states at the Fermi level in agreement with experiment. The calculated band structure is very similar to that of MnSb. The physical properties of both compounds are compared, and the dependence of the band structure on the direction of the spin magnetic moment is discussed in relation to the magnetic anisotropy and the magneto-optical polar Kerr effect.
TL;DR: In this paper, the spin reorientation phenomena have been found in both compounds slightly above room temperature, and anomalously large anisotropy in the saturation magnetization has been detected around the spin Reorientation temperature.
TL;DR: In this paper, the authors measured the electrical resistivity, magnetoresistance, magnetic susceptibility and magnetization of CeCu 6 in the temperature region of 0.6 K to room temperature.
Abstract: We have measured the electrical resistivity, magnetoresistance, magnetic susceptibility and magnetization of CeCu 6 in the temperature region of 0.6 K to room temperature. The magnetic property is extremely anisotropic, reflecting the orthorhombic crystal structure. The anisotropy of negative magnetoresistance can be qualitatively understood by the corresponding magnetization. We have found that CeCu 6 is a typical Kondo lattice substance, having no magnetic ordering. The Kondo temperature is estimated as 2–3 K.
TL;DR: In this paper, it was shown that Nd2Fe14B exhibits a spin reorientation from an axial arrangement to what appears to be a conical one as the temperature is lowered below ≈ K.
TL;DR: In this article, a dual-gun dc magnetron cosputtering was used to obtain a positive intrinsic anisotropy of roughly 3×106 erg/cm3, resulting in an easy axis of magnetization that is perpendicular to the plane of the film, while films with >37 at.
Abstract: Amorphous Tb‐Fe thin films have been produced by dual‐gun dc magnetron cosputtering, which allows a moderate range of compositions (spanning about 20 at. %) to be deposited in a single run under identical conditions. The films exhibit clean M‐H loops and torque curves which are somewhat anomalous but show consistent trends. Films deposited at room temperature with a composition in the range 17–30 at. % Tb showed a positive intrinsic anisotropy of roughly 3×106 erg/cm3, resulting in an easy axis of magnetization that is perpendicular to the plane of the film, while films with >37 at. % Tb had a small negative intrinsic anisotropy (ca. −2×105 erg/cm3). The temperature dependence of the anisotropy indicates that neither uniaxial stress nor shape anisotropy can account for most of the intrinsic uniaxial anisotropy observed, so we hypothesize that the large anisotropy must be due to pair ordering or a local anisotropy field.
TL;DR: In this article, the influence of tensile stress annealing on the magnetic properties of amorphous alloys is reported for ribbons belonging to the pseudo ternary system (FeCoNi) 75 Si 15 B 10.
Abstract: The influence of tensile stress annealing on the magnetic properties of amorphous alloys is reported for ribbons belonging to the pseudo ternary system (FeCoNi) 75 Si 15 B 10 . Ribbons of compositions (Co 1-x Fe x ) 75 Si 15 B 10 are susceptible to stress annealing in the whole composition range 0 \leq x \leq 1 . A very large easy ribbon axis anisotromy can be produced in the range 0.2 \leq x \leq 0.7 whereas the largest hard ribbon axis anisotropy is producable in the composition range around x=0.15. Ribbons of compositions [CO 1-x (Fe 0.5 Ni 0.5 ) x ] 75 Si 15 B 10 are found susceptible to stress annealing only in the range 0 \leq x \leq 0.7 . In all the compositions the induced easy ribbon axis anisotropies are irreversible whereas the hard ribbon axis anisotropies are recoverable with activation energies ≥ 1.55 eV.
TL;DR: In this paper, the authors present the first direct evidence of structural anisotropy due to anelastic polarization produced by mechanical creep, in the form of the anisotropic diffraction intensities observed by energy dispersive x-ray diffraction method.
Abstract: We present the first direct evidence of structural anisotropy due to anelastic polarization produced by mechanical creep, in the form of the anisotropic diffraction intensities observed by energy dispersive x‐ray diffraction method. We suggest that this structural anisotropy is the origin of the creep‐induced magnetic anisotropy.
TL;DR: The origin of magnetic hardening has been examined in Fe•Nd•B magnets by correlating the magnetic properties with the microstructure and magnetic domain structure observed with electron microscopy as mentioned in this paper.
Abstract: The origin of magnetic hardening has been examined in Fe‐Nd‐B magnets by correlating the magnetic properties with the microstructure and magnetic domain structure observed with electron microscopy. Hysteresis loops and susceptibility studies show a magnetic anomaly at around 140 K. Microstructure studies reveal the presence of at least four phases with compositions Fe14R2B, Fe4NdB4, a high‐Nd‐content phase, and α‐Fe. Initial magnetization studies, magnetic viscosity data, the temperature dependence of coercivity, and magnetic domain studies all indicate domain wall pinning at grain boundaries.
TL;DR: In this article, an equation for the field dependence of nuclear T1−1 enhancement due to dipolar coupling with an electron of spin 1 2 which takes into consideration g anisotropy under slow rotation conditions was derived.
TL;DR: In this article, stress anneal induced anisotropy has been studied in metallic glass ribbons of the compositions (Co 1- x Fe x ) 75 Si 15 B 10, 0 ≤ 0.12.
TL;DR: In this article, the singularity in the magnetization curve is transformed in the case of a polycrystalline specimen, and it is demonstrated that the singular point detection theory can be extended to first-order magnetization processes (FOMP), thus allowing extremely clear and accurate measurements of critical fields.
Abstract: Ferromagnetic crystals can show discontinuous jumps in the magnetization curve for certain combinations of the anisotropy constants. These are called first‐order magnetization processes (FOMP) and have been recently observed in a large variety of compounds. We analyze the problem of how this singularity in the magnetization curve is transformed in the case of a polycrystalline specimen. The problem is the same as that of the singular point detection theory (SPD) that was originally concerned with the singularities of the anisotropy fields and with the way of enhancing them. SPD is now a widely used method for measuring anisotropy fields. In the present work it is demonstrated that SPD can be extended to FOMP, thus allowing extremely clear and accurate measurements of critical fields using polycrystalline specimens. This provides in principle a powerful method for deep investigations in the anisotropy properties of ferromagnetic and ferrimagnetic materials. In Sec. II we examine how the critical parameters...
TL;DR: In this article, the authors show that the conduction electrons play a dominant role in determining the magnetic properties of rare earth compounds, leading to the conclusion that the strong magnetic character of the Rh 4 d conduction electron plays a major role in their magnetic properties.
TL;DR: High-field magnetization measurements performed at 4.2 K along different crystal axes of hexagonal Ho-Co-17 reveal, above 20 T, magnetic transitions for field directions in the hexa- gonal plane that have not been studied before in this type of intermetallic compound.
Abstract: High-field (up to 35 T) magnetization measurements performed at 4.2 K along different crystal axes of hexagonal ${\mathrm{Ho}}_{2}$${\mathrm{Co}}_{17}$ reveal, above 20 T, magnetic transitions for field directions in the hexa- gonal plane that have not been studied before in this type of intermetallic compound. The magnetization data, analyzed in a two-sublattice model, provide accurate results for the magnetic parameters of this system.
TL;DR: In this paper, a number of ac magnetic susceptibility measurements have been carried out for chemical vapor grown intercalation compounds of M x TiS 2 (M = V, Mn, Cr, Fe, Co, and Ni; 0 ≤ x ≤ 1) over the temperature range 1.5-300 K.
TL;DR: In this article, the temperature dependence of the growth-induced uniaxial anisotropy constant Kgu of epitaxially grown bismuth-substituted garnet films of composition R3−xBixFe5O12 with R=Y has been measured in the temperature range 4.2 K≤T≤TC.
Abstract: The temperature dependence of the growth‐induced uniaxial anisotropy constant Kgu of epitaxially grown bismuth‐substituted garnet films of composition R3−xBixFe5O12 with R=Y, Lu has been measured in the temperature range 4.2 K≤T≤TC. Films with (100), (110), (112), and (111) orientation have ben investigated and exhibit a very different temperature variation of Kgu. The experimental data are compared with theoretical results based on a recently reported single‐ion theory applying to bismuth‐induced uniaxial anisotropies. Kgu is calculated in terms of the actual sublattice magnetizations inferred from the fit of the molecular field theory to the measured saturation magnetization.
TL;DR: In this article, the anisotropic mixing mechanism between the 4f states and the valence bands was investigated and the character of the ferromagnetic ground state was investigated in detail.
Abstract: For pt.III see ibid., vol.19, p.2721 (1985). Extremely strong magnetic anisotropy in the ordered phases in CeSb and CeBi is explained by the anisotropic mixing mechanism between the 4f states and the valence bands. The character of the ferromagnetic ground state is investigated in detail. The anisotropy energy calculated by using realistic valence bands is consistent with the strong anisotropy observed experimentally.
TL;DR: In this paper, the saturation magnetization of the amorphous material has been investigated in Co 100-x P x with 5 ⩽ x 26 and 12 ⩾ x ⎽ 26.