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1.
在八个(111)面磁泡膜上,观察了施加面内(in-plane)磁场后在不同晶轴方向上条状畴的消失过程,测量了条畴消失场Hs*和磁畴消失场Hk*与面内磁场的方向的关系。本文计及立方磁晶各向异性,完善了面内磁场中条畴的稳定性理论。用该理论定性地解释了实验结果的主要特点。导出了Hs*与立方各向异性及面内场方向的两种近似的理论关系,它们分别适用于面内场方向靠近和不十分靠近〈110〉晶轴的情形。它们和实验结果是大致符合的。在〈110〉晶轴上,理论关系具有下列简单的形式:Hk*<110>=Hs*<110>=Hk{1+(k1/2Ku)-[al/h(4πMs/Hk)2]2/3},此式与实验结果符合得相当好。
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Antiferromagnetic resonance results on α-RbMnCl3 · 2H2O below the Néel temperature 4.56 K are reported. At T = 1.2K we find for the anisotropy fields Hc = 440 Oe and Ha = 1510 Oe. The spin flop field at T = 1.2K is 14.62 kOe. 相似文献
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《Current Applied Physics》2009,9(3):688-690
We recently reported a possible antiferromagnetically coupled phase in a Co-rich CoFeSiB thin film, that had a partially nanocrystalline Co phase in an amorphous CoFeSiB matrix. Although an amorphous CoFeSiB film should show a ferromagnetic behavior, we observed an antiferromagnetic coupling associated with a nanocrystalline Co phase in the hysteresis-loop measurements of Co-rich CoFeSiB thin films. We ascribed the observed antiferromagnetic coupling to dense stripe domains consisting of periodically up and down domains perpendicular to the surface of the film. The configuration of the stripe domains was confirmed with magnetic force microscopy images. When a longitudinal magnetic field was applied, the size of the stripe domain was reduced. While for a transverse field, the domain structure became tilted and zigzagged, but no in-plane magnetic anisotropy was noted. When the magnetic field was increased to values above the saturation magnetic field, HS = 2.5 kOe, the domain structure disappeared. 相似文献
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E. Lima Jr. T.B. Martins H.R. Rechenberg G.F. Goya C. Cavelius R. Rapalaviciute S. Hao S. Mathur 《Journal of magnetism and magnetic materials》2008
The magnetic behavior of polycrystalline yttrium orthoferrite was studied from the experimental and theoretical points of view. Magnetization measurements up to 170 kOe were carried out on a single-phase YFeO3 sample synthesized from heterobimetallic alkoxides. The complex interplay between weak-ferromagnetic and antiferromagnetic interactions, observed in the experimental M(H) curves, was successfully simulated by locally minimizing the magnetic energy of two interacting Fe sublattices. The resulting values of exchange field (HE=5590 kOe), anisotropy field (HA=0.5 kOe) and Dzyaloshinsky–Moriya antisymmetric field (HD=149 kOe) are in good agreement with previous reports on this system. 相似文献
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A. Gholizadeh N. TajaborM. Behdani M. KriegischF. Kubel M. SchönhartF. Pourarian R. Grössinger 《Physica B: Condensed Matter》2011,406(18):3465-3469
In this work, the structural and magnetic properties of Tb3 (Fe28−xCox) V1.0 (x=0, 3, 6) compounds have been investigated. The structural characterization of compounds by X-ray powder diffraction is an evidence for a monoclinic Nd3(Fe, Ti)29-type structure (A2/m space group). The refined lattice parameters a and b (but not c) and the unit cell volume V, obtained from the XRD data by the Rietveld method, are found to decrease with increasing Co concentration. The unit cell parameters behavior has been attributed to the smaller Co atoms and a preferential substitution of Fe by Co. The anisotropy field (Ha) as well as critical field (Hcr) was measured using the singular point detection (SPD) technique from 5 to 300 K in a pulsed magnetic field of up to 30 T. At T=5 K, a FOMP of type 2 was observed for all samples and persists at all temperatures up to 300 K. For sample x=0, Hcr=10.6 and 2.0 T at 5 and 300 K, respectively, is equal to that reported earlier. The occurrence of canting angles between the magnetic sublattices during the magnetization process instead of high-order anisotropy contributions (at room temperature are usually negligible) has been considered to explain the survival of the FOMP at room temperature. The anisotropy and critical fields behave differently for samples with x=0, 3 compared with x=6. The observed behavior has been related to the fact that the Co substitution for Fe takes place with a preferential entrance in the inequivalent crystallographic sites of the 3:29 structure. The contribution of the Tb-sublattice in the Tb3(Fe, V)29 compound with uniaxial anisotropy has been scaled from the anisotropy field measured on a Y3(Fe, V)29 single crystal with easy plane anisotropy. 相似文献
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Strain in the La0.67Ca0.33MnO3 films has been tuned by varying substrate and film thickness, and its effects on magnetic anisotropy are studied based on the measurements of isothermal magnetization. Measuring the strain in the films by the out-of-plane lattice parameter (c), we found a strong dependence of the magnetic anisotropy constant (Ku) on strain. Ku decreases linearly from ∼−1.1×106 erg/cm3 for c=0.763 nm to 1.2×106 erg/cm3 for c=0.776 nm, corresponding to a change from tensile strain to compressive strain. Positive Ku signifies a uniaxial anisotropy with the easy axis perpendicular to the film plane, while negative Ku demonstrates an anisotropy of the easy plane character. Smaller or larger c leads a decrease or increase in Ku, which indicates the presence of other effects in addition to those associated with strain. Three distinctive processes for the magnetization are observed along the hard magnetic axis of the films on (001)SrTiO3, suggesting a possibility of strain relaxation even in ultra-thin films. 相似文献
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Takasuke Matsuo Masami Tatsumi Hiroshi Suga Syûzô Seki 《Solid State Communications》1973,13(11):1829-1831
The heat capacity of SnCl2·2H2O single crystal was measured in the close vicinity of the phase transition temperature, Tc = 217.994 ± 0.01 K. Its anomalous part ΔC could be expressed as ΔC = A± ⊥ (T ? Tc)/Tc⊥-α±, where α+ = 0.492 ± 0.02, α- = 0.492 ± 0.02, A+ = 1.148 JK?mol?, and A- = 1.155 JK?mol?. A quasi-isothermal absorption of the enthalpy amounting to 34 J mol? was observed at Tc. 相似文献
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Jeevan JalliYang-Ki Hong Gavin S. AboSeok Bae Jae-Jin LeeJi-Hoon Park Byoung C. ChoiSeong-Gon Kim 《Journal of magnetism and magnetic materials》2011,323(21):2627-2631
Magnetic domain patterns in bulk barium ferrite (BaFe12O19; BaM) single crystals on the basal plane and the prism plane were measured and studied by magnetic force microscopy (MFM). The surface domain pattern is in the form of flowers or star on the basal plane and long elongated spikes or stripe domains on the prism plane. The change in domain structure with applied field (Happ) and the thickness (T) dependence on domain width (δ) was observed. The domain width decreased from 32 to 9 μm for the crystals of 800-100 μm thicknesses, respectively. 相似文献
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In Yb3Fe5O12, the exchange effective field can be expressed as Heff=−λ·MFe=−λχeff·He=−γ·He where γ is named as the exchange field parameter and He is the external magnetic field. Then, in this paper, by the discussions on the characteristics of the exchange field parameter γ, the properties of exchange interaction in ytterbium iron garnet (Yb3Fe5O12) are analyzed under extreme conditions (high magnetic fields and low temperatures). Our theory suggests that the exchange field parameter γ is the function of the temperatures under different external magnetic fields, and γ=a+b·T+c·T2, where the coefficients a, b, c are associated with the external magnetic fields and the magnetized directions. Thus, the temperature-dependence, field-dependence and anisotropic characteristics of the exchange interaction in Yb3Fe5O12 are revealed. Also, excellent fits to the available experiments are obtained. 相似文献
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L.J. Azevedo W.G. Clark G. Deutscher R.L. Greene G.B. Street L.J. Suter 《Solid State Communications》1976,19(3):197-201
A measurement of the temperature and angular dependence of the upper critical magnetic field Hc2 in crystals of polymeric (SN)x is reported. A large anisotropy is observed at all temperatures with Hc26 = 8.1 ± 0.4 kOe parallel to, and Hc2⊥ = 870 ± 80 Oe perpendicular to, the polymer axis at 0°K. The results are explained in terms of the polymeric crystal structure and fibrous morphology of (SN)x. 相似文献
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S.S. Kalyan Kamal P.K. Sahoo L. Durai P. Ghosal M. Manivel Raja S. Ram 《Journal of magnetism and magnetic materials》2012
Small crystallites of a metastable phase Co0.5Pt0.5 are precipitated by heating a rheological liquid precursor of cobalt–hydrazine complex and platinum chloride H2PtCl6·xH2O in polymer molecules of poly(vinylpyrrolidone) (PVP) in ethylene glycol. The hydrazine co-reduces nascent atoms from the Co2+ and Pt4+ that recombine and grow as Co0.5Pt0.5. The PVP molecules cap a growing Co0.5Pt0.5 as it achieves a critical size so that it stops growing further in given conditions. X-ray diffraction pattern of a recovered powder reveals a crystalline Co0.5Pt0.5 phase (average crystallite size D∼8 nm) of a well-known Fm3m-fcc crystal structure with the lattice parameter a=0.3916 nm (density ρ=14.09 g/cm3). A more ordered L10 phase (ρ=15.91 g/cm3) transforms (D≥25 nm) upon annealing the powder at temperature lesser than 700 °C (in vacuum). At room temperature, the virgin crystallites bear only a small saturation magnetization Ms=5.54 emu/g (D=8 nm) of a soft magnet and it hardly grows on bigger sizes (D≤31 nm) in a canted ferromagnetic structure. A rectangular hysteresis loop is markedly expanded on an optimally annealed L10 phase at 800 °C for 60 min, showing a surface modified coercivity Hc=7.781 kOe with remnant ratio Mr/Ms=0.5564, and Ms=39.75 emu/g. Crystallites self-assembled in an acicular shape tailor large Hc from ideal single domains and high magnetocrystalline anisotropy of a hard magnet L10 phase. 相似文献
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The magnetic domain structures of Fe78.8−xCoxCu0.6Nb2.6Si9B9 (x=0, 20, 40, 60) alloys are investigated by Lorentz microscopy coupled with the focused ion beam method. The specimen prepared using the FIB method is found to have a considerably more uniform thickness compared to that prepared using the ion-milling method. In Fe38.8Co40Cu0.6Nb2.6Si9B9 and Fe18.8Co60Cu0.6Nb2.6Si9B9 alloys, 180° domain walls extending in the direction of the induced magnetic anisotropy are observed. Analysis with Lorentz microscopy reveals that the width of the magnetic domains decreases with an increase in the cobalt content or the induced magnetic anisotropy Ku, that is, the domain width d is proportional to the induced magnetic anisotropy (Ku)−1/4. On the other hand, in the in situ Lorentz microscopy observation as a function of temperature, magnetic ripple structures are found to appear in a localized area due to the fluctuation of magnetization vectors from 423 K. It is observed that the induced magnetic anisotropy caused by the applied magnetic field at 803 K is not suppressed by the magnetic ripple structures observed at 423–443 K. 相似文献
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M.I. KobetsK.G. Dergachev E.N. Khatsko S.L. GnatchenkoL.N. Bezmaternykh V.L. Temerov 《Physica B: Condensed Matter》2011,406(18):3430-3435
The AFMR spectra of the NdFe3(BO3)4 crystal are measured in a wide range of frequencies and temperatures. It is found that by the type of its magnetic anisotropy the compound is an “easy-plane” antiferromagnet with a weak anisotropy in the basal plane. The effective magnetic parameters are determined: anisotropy fields Ha1=1.14 kOe and Ha2=60 kOe and magnetic excitation gaps Δν1=101.9 GHz and Δν2=23.8 GHz. It is shown that commensurate-incommensurate phase transition causes a shift in resonance field and a considerable change in absorption line width.At temperatures below 4.2 K nonlinear regimes of AFMR excitation at low microwave power levels are observed. 相似文献
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K.V.S.Rama Rao S.L. Pinjare T. Rajasekharan C. Ramasastry 《Journal of Physics and Chemistry of Solids》1980,41(1):7-10
The observation of NMR signals from 55Mn nuclei in Mn2Sb has been reported. A temperature variation study of the domain and domain wall signals in Mn2Sb confirms that the magnetization is aligned parallel to the c-axis at temperatures higher than 240 K and that it is in the basal plane below 240 K. The temperature dependence of the anisotropy in the hyperfine field at the Mn(I) and Mn(II) sites has been determined. 相似文献
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W.E. Wallace M. Merches G.K. Shenoy P.J. Viccaro 《Journal of Physics and Chemistry of Solids》1982,43(1):55-58
The bulk magnetic properties and 166Er Mössbauer spectra of Er2?xPrxCo17 pseudo-binaries are reported. Incorporation of Pr into Er2Co17 increases the anisotropy field (HA) and the saturation magnetization, while resulting in only a slight (5%) decrease in the Curie temperature. The quadrupole interaction deduced from the Mössbauer spectrum suggests that Pr preferentially substitutes for Er in Er2Co17 at the 2d site. The rise in HA is a consequence of the preferential substitution, which occurs because spatial constraints at the 2d site are less for the larger Pr3+ ion. Coupling between Er-Co and Pr-Co is found to be antiferromagnetic and ferromagnetic, respectively. 相似文献