共查询到20条相似文献,搜索用时 796 毫秒
1.
B. B. Straumal A. A. Myatiev P. B. Straumal A. A. Mazilkin S. G. Protasova E. Goering B. Baretzky 《JETP Letters》2010,92(6):396-400
The complete solubility of an impurity in a polycrystal increases with decreasing grain size, because the impurity dissolves
not only in the crystallite bulk but also on the grain boundaries. This effect is especially strong when the adsorption layers
(or the grain boundary phases) are multilayer. For example, the Mn solubility in the nanocrystalline films (where the size
of grains is ∼20 nm) is more than three times greater than that in the ZnO single crystals. The thin nanocrystalline Mn-doped
ZnO films in the Mn concentration range 0.1–47 at % have been obtained from organic precursors (butanoates) by the “liquid
ceramic” method. They have ferromagnetic properties, because the specific area of the grain boundaries in them is greater
than the critical value [B.B. Straumal et al., Phys. Rev. B 79, 205206 (2009)]. The high-resolution electron transmission microscopy studies show that the ZnO nanocrystalline grains with
the wurtzite lattice are separated by amorphous layers whose thickness increases with the Mn concentration. The morphology
of these layers differs greatly from the structure of the amorphous prewetting films on the grain boundaries in the ZnO:Bi2O3 system. 相似文献
2.
The ferromagnetic resonance in Y3Fe5−x
GaxO12 (0⩽x⩽0.63), iron garnet films obtained by liquid phase epitaxy on substrates of gadolinium gallium garnet is studied at temperatures
of 213–353 K. It is found that in the case of liquid phase epitaxy the distribution coefficient of the gallium in the films
varies from 2.2 to 4.0, depending on the composition and growth conditions. It is found that the resonance magnetic fields
can be temperature stabilized through temperature-induced changes in the saturation magnetization and anisotropy field.
Zh. Tekh. Fiz. 68, 46–50 (September 1998) 相似文献
3.
Thin films of biphase (amorphous/crystalline) magnetic Sm-Fe-Ta-N nanodroplets were fabricated at room temperature with 157 nm pulse laser deposition in nitrogen from a Sm13.8Fe82.2Ta4.0 target. The 50-100 nm biphase spherical nanodroplets consist of a 5-10 nm internal crystal portion surrounded by the external amorphous phase. Nitrogen fixation in the nanodroplets occurred in the plume. The films exhibit a ferromagnetic response of 2.5 kOe coercivity at room temperature. With further annealing and thermal treatment in nitrogen, the coercivity was increased to 5.0 kOe. The surrounding amorphous layer prevents post-ablation oxidization of the crystalline magnetic nucleus of the nanodroplet. 相似文献
4.
F. Kokai M. Taniwaki M. Ishihara Y. Koga 《Applied Physics A: Materials Science & Processing》2002,74(4):533-536
We deposited amorphous thin films of boron carbide by pulsed laser deposition using a B4C target at room temperature. As the laser fluence increased from 1 to 3 J/cm2, the number of 0.25–5 μm particulates embedded in the films decreased, and the B/C atomic ratio of the films increased from
1.8 to 3.2. The arrival of melt droplets, atoms, and small molecular species depending on laser fluence appeared to be involved
in the film formation. In addition, with increasing fluence the nanoindentation hardness of the films increased from 14 to
32 GPa. We believe that the dominant factor in the observed increase in the films’ hardness is the arrival of highly energetic
ions and atoms that results in the formation of denser films.
Received: 23 March 2001 / Accepted: 1 July 2001 / Published online: 2 October 2001 相似文献
5.
Wee Ong Siew Seong Shan Yap Cécile Ladam Øystein Dahl Turid Worren Reenaas Teck Yong Tou 《Applied Physics A: Materials Science & Processing》2011,104(3):877-881
Nanosecond-pulsed KrF (248 nm, 25 ns) and Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) lasers were used to ablate a polycrystalline
Si target in a background pressure of <10−4 Pa. Si films were deposited on Si and GaAs substrates at room temperature. The surface morphology of the films was characterized
using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Round droplets from 20 nm to 5 μm were detected
on the deposited films. Raman Spectroscopy indicated that the micron-sized droplets were crystalline and the films were amorphous.
The dependence of the properties of the films on laser wavelengths and fluence is discussed. 相似文献
6.
P. Scardi M. Leoni G. Ausanio V. Iannotti L. Lanotte 《Applied Physics A: Materials Science & Processing》2005,81(1):143-146
The relation between structural and magnetic properties of Co-Ni-Cr-Al-Y-N thin films deposited by reactive r.f. magnetron sputtering was investigated. A marked change in the magnetic behaviour of the films with the different nitrogen partial pressure in the Ar/N2 deposition atmosphere was observed and qualitatively explained in correlation with the phase composition. The nanocrystalline metal solid-solution obtained at low N2 content and the nanocrystalline nitride/amorphous composite obtained at high N2 content are not magnetic, whereas the amorphous phase produced for intermediate N2 pressures behaves like a ferromagnetic semi-permanent material. The results demonstrate the possibility of modulating the magnetic properties of r.f. magnetron sputtered Co-Ni-Cr-Al-Y-N thin films, thus opening a new route for magnetic multilayer deposition. PACS 68.55.-a; 75.70.Ak; 75.75.+a; 85.70.-w 相似文献
7.
Dynamic self-organization of magnetic domains is observed in amorphous gadolinium-cobalt films in narrow temperature intervals
on both sides of the magnetic compensation point. Spiral dynamic domains form in a limited range of ac magnetic field amplitudes
and frequencies.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 11, 688–692 (10 December 1997) 相似文献
8.
Yu. V. Goryunov I. A. Garifullin Th. Mühge H. Zabel 《Journal of Experimental and Theoretical Physics》1999,88(2):377-384
The ferromagnetic resonance and magnetization of single-crystal thin (27–100 Å films grown in the (110) direction are measured
in the temperature range 20–400 K. The films are prepared by molecular-beam epitaxy on single-crystal sapphire
substrates with a Nb(110)buffer layer. The angular dependence of the parameters of the ferromagnetic resonance spectrum is
observed to have a 180° character when the static magnetic field is rotated in the plane of the sample. It is established
that this angular dependence can be described on the assumption that the lattice distortions are essentially trigonal. A comparative
analysis of previous data for Fe(001) films with the data for Fe(110) films shows that the source of the corrections to the
cubic anisotropy constant is the characteristic distribution of the strains along the thickness of the film.
Zh. éksp. Teor. Fiz. 115, 689–703 (February 1999) 相似文献
9.
V. V. Shagaev 《Physics of the Solid State》1998,40(11):1892-1895
Analytical expressions are derived for the derivatives of the frequencies of magnetostatic waves with respect to the external
magnetic field in anisotropic ferromagnetic films. Films having cubic anisotropy and 〈100〉, 〈110〉, and 〈111〉 surfaces are
analyzed in detail. The frequency-field relations are used in an experimental determination of the temperature coefficients
of the cubic anisotropy field and the saturation magnetization in an yttrium iron garnet film.
Fiz. Tverd. Tela (St. Petersburg) 40, 2089–2092 (November 1998) 相似文献
10.
M. B. Agranat S. I. Ashitkov A. V. Kirillin A. V. Kostanovskii V. E. Fortov S. I. Anisimov P. S. Kondratenko 《JETP Letters》1997,66(10):699-703
Observations of microcrystalline graphite subjected to picosecond laser pulses reveal the formation of a liquid phase with
a subsequent transition to a uniform amorphous state of a surface layer upon solidification. This phenomenon is observed on
a definite type of graphite and with the radiation incident on a plane parallel to the sixfold symmetry axis, and only for
certain parameters of the laser pulse. A structural analysis of the amorphous phase is performed by electron microscopy and
Raman scattering spectroscopy. A periodic structure with a period of the order of the wavelength of the heating pulse is formed
in the heating region. The “rulings” of this periodic structure are oriented in the direction of polarization of the heating
pulse. A study of the reflection kinetics of the probe laser pulse showed that the characteristic existence time of the liquid
phase and of the solidification process is ∼10−10 s.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 10, 661–665 (25 November 1997) 相似文献
11.
W. Felsch 《Zeitschrift für Physik A Hadrons and Nuclei》1969,219(3):280-299
In a previous paper a method has been described to produce thin films of amorphous iron by simultaneous condensation of iron and small additions of oxygen, silicon, or germanium onto a substrate at 20 °K. During annealing the amorphous films crystallize within a narrow range of temperature. In this paper the magnetic properties of these films are investigated. By a new lowtemperature ?gnetometer the magnetization curves can be registered for the different states of annealing. It results that even in the amorphous state iron is ferromagnetic. Below a critical concentration of the oxygen, silicon, or germanium admixtures the magnetic moment of the iron atoms is smaller and the coercive force is greater in the amorphous than in the crystalline structure. Above that concentration the magnetic moments in the two structures are equal, whereas the coercive force of the amorphous films is smaller than that of the crystalline ones. The results are explained by a concentration depending short range order in the amorphous films. 相似文献
12.
Summary Polycrystalline thin films of the ferromagnetic semiconductor HgCr2Se4 have been prepared for the first time on insulating MgAl2O4 single-crystal substrates by molecular-beam deposition and subsequent annealing with HgSe. The optimum conditions for preparing
single-phase thin films of HgCr2Se4 were obtained. The magnetoresistance and Hall effects of these films were measured from 77 to 295 K in magnetic fields up
to 1.19·106 A/m. It becomes evident that these electrical properties of the films are affected by the interdiffusion layers in the films
near the substrates or the magnetically disordered layers such as amorphous or grain boundaries in the films.
Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16,
1982. 相似文献
13.
Amorphous copper-doped ZnO thin films (ZnO:Cu) prepared on glass substrates by the radio-frequency magnetron co-sputtering have been investigated. Magnetic measurements indicated that the amorphous ZnO:Cu thin films were ferromagnetic at room temperature and the saturation magnetization was much higher than that of the polycrystalline films. X-ray diffraction results showed there was no Cu2O phase in amorphous ZnO:Cu films, which might be the reason for the high magnetic moment of the films. On the other hand, the high saturation magnetization of the amorphous ZnO:Cu films could also attribute to that there was no limit of solid solubility of Cu in amorphous ZnO solvent. The X-ray photoelectron spectroscopy study of the amorphous ZnO:Cu thin films reveal that copper was in Cu2+ chemical state. 相似文献
14.
V. V. Randoshkin V. I. Kozlov V. Yu. Mochar N. V. Vasil’eva N. A. Es’kov Yu. A. Durasova 《Physics of the Solid State》1999,41(7):1144-1148
The characteristic features of ferromagnetic resonance (FMR) were studied in bismuth-containing single-crystal iron-garnet
films (BSIGFs) with no rapidly relaxing ions and relatively weak orthorhombic magnetic anisotropy (ORMA). The films were grown
on (110) and (210) substrates by liquid-phase epitaxy from a supercooled flux solution. Attention is focused mainly on the
unidirectional magnetic anisotropy in the film plane and on the effect of the film/substrate transitional surface layer on
the FMR spectrum.
Fiz. Tverd. Tela (St. Petersburg) 41, 1254–1258 (July 1999) 相似文献
15.
Adam Abdalla Elbashir Adam Xiaomin Cheng Xiawei Guan Xiangshui Miao 《Applied Physics A: Materials Science & Processing》2014,117(4):2115-2119
In this work, an effective method to modulate the ferromagnetic properties of Mn-doped GeTe chalcogenide-based phase change materials is presented. The microstructure of the phase change magnetic material Ge1?x Mn x Te thin films was studied. The X-ray diffraction results demonstrate that the as-deposited films are amorphous, and the crystalline films are formed after annealing at 350 °C for 10 min. Crystallographic structure investigation shows the existence of some secondary magnetic phases. The lattice parameters of Ge1?x Mn x Te (x = 0.04, 0.12 and 0.15) thin films are found to be slightly different with changes of Mn compositions. The structural analysis clearly indicates that all the films have a stable rhombohedral face-centered cubic polycrystalline structure. The magnetic properties of the amorphous and crystalline Ge0.96Mn0.04Te were investigated. The measurements of magnetization (M) as a function of the magnetic field (H) show that both amorphous and crystalline phases of Ge0.96Mn0.04Te thin film are ferromagnetic and there is drastic variation between amorphous and crystalline states. The temperature (T) dependence of magnetizations at zero field cooling (ZFC) and field cooling (FC) conditions of the crystalline Ge0.96Mn0.04Te thin film under different applied magnetic fields were performed. The measured data at 100 and 300 Oe applied magnetic fields show large bifurcations in the ZFC and FC curves while on the 5,000 Oe magnetic field there is no deviation. 相似文献
16.
Rakesh Malik S. Annapoorni S. Lamba S. Mahmood R. S. Rawat 《Applied Physics A: Materials Science & Processing》2011,105(1):233-238
Nickel ferrite thin films were deposited by a pulsed laser deposition (PLD) technique on silicon substrate at room temperature
in a vacuum of 5×10−5 mbar. The films were subjected to different annealing temperatures from 300–900°C and were also exposed to single shot energetic
hydrogen ions using a Dense Plasma Focus (DPF) device. The changes induced in the films exposed at different distances from
the top of the anode were investigated. The structural, morphological and magnetic properties of the annealed and exposed
samples were investigated. X-ray diffraction (XRD) studies reveal the presence of a single phase of nickel ferrite after annealing.
SEM micrographs indicate an increase in the grain size, both on annealing as well as on exposure to hydrogen ions. Annealing
and hydrogen ion irradiation induced an enhancement in the magnetic moments. Laser droplets which are inherent in films deposited
by laser ablation were found to be dispersed as a result of single shot hydrogen ion irradiation from the DPF. 相似文献
17.
A. D.?Rata A.?Herklotz L.?Schultz K.?D?rr 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,76(2):215-219
We investigate the structure and magnetic properties of
thin films of the LaCoO3 compound. Thin films are deposited
by pulsed laser deposition on various substrates in order to tune
the strain from compressive to tensile. Single-phase (001)
oriented LaCoO3 layers were grown on all substrates despite
large misfits. The tetragonal distortion of the films covers a
wide range from -2% to 2.8%. Our LaCoO3 films are
ferromagnetic with Curie temperature around 85 K, contrary to the
bulk. The total magnetic moment is below 1μ
B
/Co3+, a
value relatively small for an exited spin-state of the Co3+
ions, but comparable to values reported in literature. A
correlation of strain states and magnetic moment of Co3+ ions
in LaCoO3 thin films is observed. 相似文献
18.
Laser-induced periodic surface structures (LIPSS) were generated on oriented and amorphous thick, as well as on spin-coated
thin, poly-carbonate films by polarized ArF excimer laser light. The influence of the film structure and thickness on the
LIPSS formation was demonstrated. Below a critical thickness of the spin-coated films the line-shaped structures transformed
into droplets. This droplet formation was explained by the laser-induced melting across the whole film thickness and subsequent
de-wetting on the substrate. The thickness of the layer melted by laser illumination was computed by a heat-conduction model.
Very good agreement with the critical thickness for spin-coated films was found. The original polymer film structure influences
the index of refraction of the thin upper layer modified by the laser treatment, as was proven by the dependence of the structure’s
period on the angle of incidence both for ‘s’- and ‘p’-polarized beams. The effect of the original surface roughness – grains in thick films or holes in thin films –
was studied using atomic force microscopy. It was shown that the oblique incidence of ‘s’-polarized beams results in an intensity confinement in the direction of the forward scattering and in asymmetrical interference
pattern formation around these irregularities. A new, two-dimensional grating-like structure was generated on spin-coated
films. These gratings might be used as a special kind of mask.
Received: 10 July 2001 / Accepted: 23 July 2001 / Published online: 30 August 2001 相似文献
19.
The nonlinear dynamics of a periodic system of interacting domain walls in a thin ferromagnetic uniaxial film with transverse
anisotropy is examined. The interaction between the domain walls takes place through the magnetostatic demagnifying fields
of the domains. The equations of motion derived for such a system of walls are solved numerically by a 4–5th-order Runge-Kutta
scheme, while the uniformity of the distributions of the phase trajectory, the form of the Poincaré cross section, and the
spectral density of the vibrations serve as indicators of the type of oscillations. All the known types of oscillations are
observed in a computer simulation of this nonlinear system: periodic, quasiperiodic, and chaotic. The computational results
have a universal character for uniaxial, highly-anisotropic ferromagnetic films having a strip domain structure, since the
results can be easily scaled for materials with different magnetic characteristics.
Fiz. Tverd. Tela (St. Petersburg) 39, 2036–2039 (November 1997) 相似文献
20.
M. Fähnle 《Applied Physics A: Materials Science & Processing》1980,23(3):267-272
For binary alloys with only one sort of magnetic atoms we have calculated, by means of computer simulations, the distribution
of magnetic dipole fields at regular lattice sites and suitably defined interstitial sites for the magnetic ground state of
amorphous ferromagnetic and speromagnetic alloys and crystalline and amorphous spin glasses. Thereby we have considered spatially
random arrangements of atoms and have neglected all magnetic correlations in the case of speromagnets and spin glasses. We
have derived symmetric and isotropic distribution functions, which are fairly well described by Gaussian distributions for
large concentrations of magnetic atoms only. The distribution functions are characterized by their second moments, which are
important for the discussion of NMR and μ+ SR relaxation rates in these materials. 相似文献