共查询到20条相似文献,搜索用时 10 毫秒
1.
Andrzej Maziewski 《Thin solid films》1981,81(2):187-194
Single-crystal films of (YCa)3(FeGe)5O12 garnets were prepared by the liquid phase epitaxial method on the (111) plane of Gd3Ga5O12 substrates. These magnetic bubble domain films have comparable uniaxial anisotropy energy, cubic anisotropy energy and demagnetizing energy. A photographic technique was developed to measure the angles of inclination of the domain magnetization vectors with respect to the normal to the sample surface. Without an applied magnetic field these inclination angles were 58° and 122°. A simple stripe domain model was used to provide an explanation of the experimental results. This model can easily be extended for other types of mixed anisotropy cases. 相似文献
2.
E.A. GiessB.E. Argyle B.A. CalhounD.C. Cronemeyer E. KlokholmT.R. McGuire T.S. Plaskett 《Materials Research Bulletin》1971
(RE,Y)3(Fe,Ga)5O12 garnets, where RE=Eu or Gd, have been developed for use as magnetic bubble domain materials. Magnetic and crystallographic studies were used to find suitable compositions for epitaxial thin films on nonmagnetic garnet substrate crystals. Properties of films grown by liquid phase epitaxy on Czochralski Gd-Ga garnet (111) substrates are discussed. Uniaxial anisotropy in the films can be interpreted as being the result of a lattice mismatch stress mechanism. The Gd-Y films with uniaxial anisotropy are in tension while the Eu-Y films are in compression as shown by lattice spacing differences between films and their substrates. Uncracked, high stability Eu-Y films with very high compressive stresses were grown. Annealing experiments reveal significant changes in anisotropy which correlate with large changes in film lattice spacing. Thus, it is possible to obtain high uniaxial anisotropy in garnets containing only one kind of rare earth ion together with a nonmagnetic ion such as yttrium. These films support domains with very high wall velocities at typical device drive fields. 相似文献
3.
Growth-induced anisotropy, Ku , in bubble garnet films containing La and Eu or Sm has been found to be anomalous compared to that produced by Eu or Sm and smaller ions such as Y or Lu. In 相似文献
4.
Mixed rare earth iron garnet films containing calcium and germanium have been grown on (111) oriented gadolinium gallium garnet (GGG) substrates. The effect of growth conditions on film composition and properties is discussed. The 5 μm diameter bubble films have good magnetic properties; however, temperature control during film growth is very critical. 相似文献
5.
The stress patterns associated with various defects in Czochralski-grown gadolinium gallium garnet (GGG) crystals have been observed using a polarizing microscope. The effect of these defects on both the surface topography and the magnetic behaviour of epitaxial magnetic garnet films grown on GGG substrates is reported. In particular, iridium inclusions and defects of a filamentary nature affect the surface topography. Other types of defect influence the magnetic behaviour of the films in a manner attributable to a change in the lattice parameter. 相似文献
6.
The anisotropy field of magnetic bubble garnet films grown by LPE is an important property to be controlled as well as the bubble collapse field and the strip width. The anisotropy field is comparatively likely to drift with run number even if the characteristic length can be kept constant and directly affects the device operation. In order to suppress the drift of the anisotropy field, the melt compositional drift must be suppressed by the periodic addition of garnet oxides and flux to the melt. 相似文献
7.
Kamara S Terki F Dumas R Dehbaoui M Sadowski J Galéra RM Tran QH Charar S 《Journal of nanoscience and nanotechnology》2012,12(6):4868-4873
We explore the magnetic anisotropy of GaMnAs ferromagnetic semiconductor by Planar Hall Effect (PHE) measurements. Using low magnitude of applied magnetic field (i.e., when the magnitude H is smaller than both cubic Hc and uniaxial Hu anisotropy field), we have observed various shapes of applied magnetic field direction dependence of Planar Hall Resistance (PHR). In particular, in two regions of temperature. At T < Tc/2, the "square-shape" signal and at T > Tc/2 the "zigzag-shape" signal of PHR. They reflect different magnetic anisotropy and provide information about magnetization reversal process in GaMnAs ferromagnetic semiconductor. The theoretical model calculation of PHR based on the free energy density reproduces well the experimental data. We report also the temperature dependence of anisotropy constants and magnetization orientations. The transition of easy axis from biaxial to uniaxiale axes has been observed and confirmed by SQUID measurements. 相似文献
8.
M.T. Elliott 《Materials Research Bulletin》1974,9(9):1143-1149
Ferromagnetic resonance techniques have been used to measure the growth-and stress-induced uniaxial magnetic anisotropy of LPE grown garnet films of the nominal composition Y1.64Eu0.10Lu0.30Ca0.96Ge0.96Fe4.04O12 from 130°K to near the Curie temperature, 455°K. The longitudinal and transverse resonance fields were measured prior and subsequent to an anneal at 1453°K. The growth-induced anisotropy, KGu ~?0.03 × 104 ergs/cm3 at 300°K, was found to be approximately 10% of the stress-induced anisotropy, and of opposite sign for these tensile films. The associated anisotropy field, exhibited a reversal of slope, with a maximum occurring at 310°K. A model which assumes the existence of a surface anisotropy is proposed to explain these observations. The temperature dependence of the cubic anisotropy, the magnetization, the linewidth, and the exchange constant have been measured also. 相似文献
9.
B. Z. Rameev A. Gupta G. Miao G. Xiao F. Yildiz L. R. Tagirov B. Akta 《Technical Physics Letters》2005,31(9):802-805
The magnetic anisotropy of thin epitaxial films of chromium dioxide (CrO2) has been studied as a function of the film thickness by the ferromagnetic resonance (FMR) technique. CrO2 films with various thicknesses in the range from 27 to 535 nm have been grown on (100)-oriented TiO2 substrates by chemical vapor deposition using CrO3 as a solid precursor. In a series of CrO2 films grown on the substrates cleaned by etching in a hydrofluoric acid solution, the FMR signal exhibits anisotropy and
is strongly dependent on the film thickness. The magnetic properties of CrO2 films are determined by a competition between the magnetocrystalline and magnetoelastic anisotropy energies, the latter being
related to elastic tensile stresses caused by the lattice mismatch between the film and the substrate. In the films of minimum
thickness (27 nm), this strain-induced anisotropy is predominant and the easy magnetization axis switches from the [ 001]
crystallographic direction (characteristic of the bulk magnet) to the [ 010] direction. 相似文献
10.
K. S. Novoselov S. V. Dubonos S. V. Morozov E. W. Hill I. V. Grigorieva A. K. Geim 《Journal of Low Temperature Physics》2005,139(1-2):65-72
Movements of individual domain walls in a ferromagnetic garnet were studied with angstrom resolution. The measurements reveal
that domain walls can be locked between adjacent crystallographic planes and propagate by distinct steps matching the lattice
periodicity. 相似文献
11.
The influence of melt composition and growth temperature Tg on the growth-induced magnetic anisotropy constant Kgu in Bi substituted LPE ferrimagnetic garnet films has been investigated. In films grown from Bi2O3 based and from based melts the value of Kgu increased upon decreasing Tg, associated with an increasing incorporation of B1. However, at given Bi content the films grown from Bi2O3 based fluxes generally exhibited smaller values of Kgu than those from based melts. The addition of small amounts of Ca2+ to the Bi2O3 based melts resulted in (Y,Bi)-garnet films changing from n- to p-type electrical conductivity at a minimum value of Kgu. Additions of Si4+ to a based melt reduced the uniaxial magnetic anisotropy of La-YIG-Ga films accompanied by a change from p- to n-type conductivity. Similarly, (Gd,Bi)-garnet films from based melts changed from n- to p-type conductivity upon decreasing Tg where Kgu changes sign from negative to positive. From the temperature dependence of the electrical conductivity the electron and hole concentrations in some of these films were estimated suggesting that the sign change of Kgu in the investigated (Gd,Bi)-garnet films and the minimum of Kgu in the investigated (Y,Bi)-garnet films and (La,Y)-garnet films occur at donor-acceptor compensation. This experimental evidence led us to conclude that the growth induced magnetic anisotropy may be correlated with the presence of donor and acceptor centers in the garnet structure. 相似文献
12.
A new method for selecting iron-yttrium garnet (IYG) film compositions is proposed and experimentally verified. Using this approach, it is possible to obtain thick IYG films with high magnetic characteristics. 相似文献
13.
Field induced magnetic-anisotropy is a very important but poorly understood property. There have been many hypotheses on the origin of the phenomenon, e.g. strain, atomic pair ordering, etc., but little experimental evidence exist. This study prepares 100 nm thick Permalloy films having the field-induced-magnetic-anisotropy and carefully measure strains, i.e. interplanar distance of crystallographic (111) planes in various directions, using high power synchrotron radiation and precise Grazing Incidence X-Ray Diffraction method. The result delineates that the field-induced-magnetic-anisotropy has a strong correlation with the strain-anisotropy in the film. 相似文献
14.
The effects of laser annealing Ga-substituted EuYIG epitaxial films in still, controlled ambients of air and one to five atmospheres of pure oxygen have been studied. An approximately logarithmic increase in saturation magnetization (4pi M_{s} ) and decrease in film magnetic Q factor were observed with increasing oxygen pressure in the annealing ambient. Compared with the most successful previous experiments, annealing at five atmospheres of oxygen displaced nearly twice the fraction of Ga from tetrahedral to octahedral lattice sites. As evidenced by the lack of film damage, the correlation of lattice parameter with the location of the Ga ions and the lack of broadening in the ferromagnetic resonance (FMR) lines, effective annealing temperatures above 1850K were achieved with no significant loss of oxygen from the films. The use of FMR to deduce the extent of film annealing was affirmed through the agreement of independent measurements of4piM_{s} by bubble statics and SQUID magnetometry in films indicated to be homogeneous by FMR. 相似文献
15.
Vetoshko P. M. Gusev N. A. Chepurnova D. A. Samoilova E. V. Syvorotka I. I. Syvorotka I. M. Zvezdin A. K. Korotaeva A. A. Belotelov V. I. 《Technical Physics Letters》2016,42(8):860-864
Technical Physics Letters - A new type of f lux-gate vector magnetometer based on epitaxial yttrium iron garnet films has been developed and constructed for magnetocardiography (MCG)... 相似文献
16.
V. V. Randoshkin N. V. Vasil’eva V. G. Plotnichenko Yu. N. Pyrkov 《Technical Physics Letters》2000,26(12):1053-1054
The optical absorption of di-and trivalent cobalt ions embedded in single-crystalline films of gadolinium gallium garnet was
observed in the samples grown by liquid-phase epitaxy from supercooled solution melts based on PbO-B2O3 and PbO-B2O3-GeO2 systems. 相似文献
17.
An automated spatial filtering apparatus used for characterization of magnetic bubble films with zero field strip widths greater than 1.5μm has been constructed. This apparatus makes measurements of the zero field period and the period in an applied magnetic field. When these two measurements are combined with measured values for the film thickness and the Neél temperature, values for relevant material parameters of the bubble films can be calculated using the Kooy and Enz theory. Details of the spatial filter apparatus, the method used for data analysis, and the accuracy of the method are discussed. 相似文献
18.
The effects of ion implantation into (SmTmY)3 (GaFe)5 O12 garnet thin films have been studied by ferromagnetic resonance. He+ ions were used for implantation with doses ranging from 3 to 4 × 1015He+/ cm2and implantation energy ranging from 150 to 175 Kev. The uniaxial and cubic anisotropy constants have been studied as a function of temperature from 0°C to 100°C for both as-grown and ion-implanted films. The implantation has effectively changed an easy-axis anisotropy to that of an easy plane in the implanted layers of the films. A cubic anisotropy constant K1 with values varying from 4 × 103to 6 × 103erg/cm3at room temperature has been observed in these films. The results also indicated that to the first order, the implanted region in the film was essentially magnetically uncoupled from the bulk of the film. 相似文献
19.
The described method for the anisotropy field measurement uses two fields HL and HT . The deviation of magnetization from the easy direction, and hence also sense signals, are proportional to these fields. The ratio of two integrated sense signals atH_{L} = 0 andH_{L} neq 0 reaches a certain value (∼ 2.5) with fieldH_{T} = H_{k} . In this way, Hk may be measured by a device designed for the coercive force measurement. 相似文献
20.
It is established that the spectrum of spin wave (SW) resonance in garnet ferrite films with linear depth profile of the effective anisotropy consists (unlike the spectrum of homogeneous films) of a series of high-intensity SW modes and modes of very low intensity. The distribution of resonance fields of high-intensity SW modes depends on the gradient of the effective anisotropy field. For the same film thickness, the number of these modes increases with the value of gradient. 相似文献