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1.
FePt (20 nm) films with AgCu (20 nm) underlayer were prepared on thermally oxidized Si (0 0 1) substrates at room temperature by using dc magnetron sputtering, and the films annealed at different temperature to examine the disorder–order transformation of the FePt films. It is found that the ordered L10 FePt phase can form at low annealing temperature. Even after annealing at 300 °C, the in-plane coercivity of 5.2 kOe can be obtained in the film. With increase in annealing temperature, both the ordering degree and coercivity of the films increase. The low-temperature ordering of the films may result from the dynamic stress produced by phase separation in AgCu underlayer and Cu diffusion into FePt phase during annealing. 相似文献
2.
M. Calixto-Rodriguez H. Martínez O. Flores A. Sanchez-Juarez P. Reyes 《Applied Surface Science》2010,256(8):2428-7591
As-deposited antimony sulfide thin films prepared by chemical bath deposition were treated with nitrogen AC plasma and thermal annealing in nitrogen atmosphere. The as-deposited, plasma treated, and thermally annealed antimony sulfide thin films have been characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, UV-vis spectroscopy, and electrical measurements. The results have shown that post-deposition treatments modify the crystalline structure, the morphology, and the optoelectronic properties of Sb2S3 thin films. X-ray diffraction studies showed that the crystallinity of the films was improved in both cases. Atomic force microscopy studies showed that the change in the film morphology depends on the post-deposition treatment used. Optical emission spectroscopy (OES) analysis revealed the plasma etching on the surface of the film, this fact was corroborated by the energy dispersive X-ray spectroscopy analysis. The optical band gap of the films (Eg) decreased after post-deposition treatments (from 2.36 to 1.75 eV) due to the improvement in the grain sizes. The electrical resistivity of the Sb2S3 thin films decreased from 108 to 106 Ω-cm after plasma treatments. 相似文献
3.
Suk J. Kim 《Solid State Communications》2004,132(6):361-364
Amorphous Co2MnSi thin film was deposited using radio-frequency sputtering. The amorphous film crystallized into a single-phased L21 structure at 500 °C, which was highly disordered. The structure was meta-stable as the crystallized film decomposed upon further heating. Increasing the annealing temperature to 600 °C precipitated fcc Co together with Co2MnSi. Magnetic measurements showed that the as-deposited amorphous film was paramagnetic, exhibiting a spin glass state below 44 K. The phase transition at 500 °C produced a ferromagnetic Co2MnSi thin film whose saturation magnetic moment was considerably lower than reported values due to the disordered structure of the crystallized film. 相似文献
4.
Shufang Wang Jinchun Cheng Songqing Zhao Mingjing Chen Jianglong Wang 《Applied Surface Science》2010,257(1):157-159
We report the laser-induced voltage (LIV) effects in c-axis oriented Bi2Sr2Co2Oy thin films grown on (0 0 1) LaAlO3 substrates with the title angle α of 0°, 3°, 5° and 10° by a simple chemical solution deposition method. A large open-circuit voltage with the sensitivity of 300 mV/mJ is observed for the film on 10° tilting LaAlO3 under a 308 nm irradiation with the pulse duration of 25 ns. When the film surface is irradiated by a 355 nm pulsed laser of 25 ps duration, a fast response with the rise time of 700 ps and the full width at half maximum of 1.5 ns is achieved. In addition, the experimental results reveal that the amplitude of the voltage signal is approximately proportional to sin 2α and the signal polarity is reversed when the film is irradiated from the substrate side rather than the film side, which suggests the LIV effects in Bi2Sr2Co2Oy thin films originate from the anisotropic Seebeck coefficient of this material. 相似文献
5.
Y.H. Fang P.C. Kuo P.L. Lin S.C. Chen C.T. Kuo G.P. Lin 《Journal of magnetism and magnetic materials》2008
When the thickness of Ag under layer is 25 nm, the CoPt/Ag film has maximum out-of-plane squareness (S⊥), minimum in-plane squareness (S∥), and the largest out-of-plane coercivity (Hc⊥), they are 0.95, 0.35, and 15 kOe, respectively. Different volume percent of SiNx ceramic materials were co-sputtered with Co50Pt50 films on the Ag under layer to reduce the grain size of the CoPt film. Comparing the X-ray diffraction pattern of CoPt-SiNx/Ag films without annealing with that of the films which annealed at 600 and 700 °C, it is found that the intensities of CoPt (0 0 1) and CoPt (0 0 2) superlattice lines were reduced after annealing. As the SiNx content is raised to 50 vol%, the particle size of CoPt is reduced to be about 9 nm. 相似文献
6.
Co-doped TiO2 films were fabricated under different conditions using reactive facing-target magnetron sputtering. Co doping improves the transformation of TiO2 from anatase phase to rutile phase. The chemical valence of doped Co in the films is +2. All the films are ferromagnetic with a Curie temperature above 340 K. The average room-temperature moment per Co of the Co-doped TiO2 films fabricated at 1.86 Pa decreases from 0.74 μB at x=0.03 to 0.02 μB at x=0.312, and decreases from 0.54 to 0.04 μB as x increases from 0.026 to 0.169 for the Co-doped TiO2 films fabricated at 0.27 Pa. The ferromagnetism originates from the oxygen vacancies created by Co2+ dopants at Ti4+ cations. The optical band gaps value (Eg) of the Co-doped TiO2 films fabricated at 1.86 Pa decreases linearly from 3.35 to 2.62 eV with the increasing x from 0 to 0.312. For the Co-doped TiO2 films fabricated at 1.86 Pa, the Eg decreases linearly from 3.26 to 2.53 eV with increasing x from 0 to 0.350. 相似文献
7.
K. AkkoucheA. Guittoum N. BoukherroubN. Souami 《Journal of magnetism and magnetic materials》2011,323(21):2542-2548
Nanostructured Fe50Co50 powders were prepared by mechanical alloying of Fe and Co elements in a vario-planetary high-energy ball mill. The structural properties, morphology changes and local iron environment variations were investigated as a function of milling time (in the 0-200 h range) by means of X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis and 57Fe Mössbauer spectroscopy. The complete formation of bcc Fe50Co50 solid solution is observed after 100 h milling. As the milling time increases from 0 to 200 h, the lattice parameter decreases from 0.28655 nm for pure Fe to 0.28523 nm, the grain size decreases from 150 to 14 nm, while the meal level of strain increases from 0.0069% to 1.36%. The powder particle morphology at different stages of formation was observed by SEM. The parameters derived from the Mössbauer spectra confirm the beginning of the formation of Fe50Co50 phase at 43 h of milling. After 200 h of milling the average hyperfine magnetic field of 35 T suggests that a disordered bcc Fe-Co solid solution is formed. 相似文献
8.
Effects of annealing in nitrogen atmosphere and HCl-etching on the photoluminescence spectra of spray-deposited CdS:In thin films 总被引:1,自引:0,他引:1
The aim of this work is to find the effect of processing on the photoluminescence (PL) of spray-deposited CdS:In thin films. So the PL spectra of the as-deposited, annealed and HCl-etched CdS:In thin films prepared by the spray pyrolysis (SP) technique were recorded at T = 23 K. The yellow and red bands were observed in the spectrum of the as-deposited film beside bands with weaker intensity in the infrared region. The PL signal was weakened by annealing in nitrogen atmosphere at T = 400 °C and HCl-etching. A deconvolution peak fit was established to find the effects of these treatments on the different bands. The spectrum of the as-deposited film was deconvoluted to 12 peaks, which were reduced to 6 peaks after both treatments. It was found that both treatments have approximately the same effects on the PL spectra; that is they removed most of the peaks and shoulders in the red and infrared regions and attenuated most of the peaks in the yellow region. Some peaks were blue-shifted after annealing which was explained by the growth of nanocrystallites due to the thermal stress that results from the different expansion coefficients of the film and the substrate. These changes were accompanied by a phase change from the mixed (cubic and hexagonal) phase to the hexagonal phase as shown in the X-ray diffractograms. 相似文献
9.
J.J. Qiu K.B. Li G.C. Han Y.K. Zheng Z.B. Guo Y.H. Wu 《Journal of magnetism and magnetic materials》2006
The influence of deposition power and seedlayer on the properties of hard magnet Co50Pt50 was studied. Co50Pt50(/Co90Fe10)/Ru/Co90Fe10 trilayer was used as pining/pinned layer in spin valves. The influences of different hard layer, soft layer and free layer on exchange bias, interlayer coupling, and magnetoresistance (MR) ratio were studied. Weak antiferromagnetic interlayer coupling was obtained by adjusting the thickness of hard and soft layers. MR of a spin valve with structure Cr2/CoFe0.5/CoPt4/CoFe0.5/Ru0.8/CoFe2.2/Cu2.05/CoFe2.6/Cu1.1/Ta1 reached 10.68% (unit in nm), which is comparable to those of IrMn-based synthetic spin valves. The increment of the coercivity of the free layer is mainly due to the static magnetic interaction between the hard layer and the free layer. 相似文献
10.
Thin films of YCa4O(BO3)3 (YCOB)-based new luminescent materials were explored by the combinatorial pulsed laser deposition (PLD) method which enabled us to fabricate continuous composition spread film libraries. Strong red and green luminescence were found in the Y1−xEuxCOB (0 ≤ x ≤ 1), (YEuCOB) and Y1−yTbyCOB (0 ≤ y ≤ 1) (YTbCOB) films, respectively. The film libraries were characterized by photoluminescence (PL), PL decay, an electron-probe microanalyzer and an electron diffraction analysis. The luminescent intensities in the amorphous film libraries strongly depended on the chemical composition of each rare-earth (RE) ion. The optimum concentration of rare-earth ions in YEuCOB and YTbCOB were experimentally determined to be Eu = 7.5% and Tb = 20-30%, respectively. 相似文献
11.
W.B. Mi 《Applied Surface Science》2010,256(9):2831-2836
Fe0.5Ge0.5 nanocomposite films with different film thicknesses were fabricated using cosputtering. The films are composed of Ge, Fe and Fe3Ge2, and are ferromagnetic at room temperature. The saturation magnetization and magnetic interaction including dipolar interaction and exchange coupling increase with the increasing film thickness. The electrical conductance mechanism turns from metallic to semiconducting and the saturation Hall resistivity ρxys increases with the decreasing film thickness. At 28 nm, ρxys is ∼137 μΩ cm at 2 K, about 150 times larger than that of pure Fe film (0.9 μΩ cm) and four orders larger than that of bulk Fe. The ρxy-H curves of all the films show the same linearity character in low-field range even though the temperature-independent slope is different at different film thicknesses. At high temperatures, the skew scattering mechanism is dominant. At low temperatures, side-jump effect should be dominant at large resistivity ρxx regime for the thin films, and the skew scattering is dominant at small ρxx regime for the thick films. 相似文献
12.
Y.K. Takahashi T. Ohkubo K. Hono S. Okamura N. Tezuka K. Inomata 《Journal of magnetism and magnetic materials》2007
The microstructures of Co2FeAl and Co2(Cr0.4Fe0.6)Al sputtered films and of their magnetic tunnel junctions (MTJs) have been investigated to discuss the possible reasons for an unexpectedly low tunneling magnetoresistance (TMR). The structure of the Co2FeAl film changed from B2 to L21 with increasing substrate temperature, while that of the Co2(Cr0.4Fe0.6)Al film remained B2 up to 500 °C. The thermodynamically predicted phase separation was not observed in the films. The low TMR values obtained from the MTJs using the Co2FeAl and Co2(Cr0.4Fe0.6)Al films are attributed to the low-spin polarization expected from the low degree of order in these films. The TMR values depend sensitively on the interfacial structure of the tunnel junctions when the degree of order of the film is low. 相似文献
13.
X.L. Zhong 《Applied Surface Science》2006,253(2):417-420
Bi3.25La0.75Ti3O12 (BLT) thin films were fabricated on Pt/Ti/SiO2/Si(1 0 0) substrates by chemical solution deposition (CSD), and the dependence of ferroelectric and dielectric properties of the as-deposited BLT thin films on excess Bi content in precursor sols was studied. It is found that the prepared BLT thin film shows the best polarization-electric field, capacitance-voltage and dielectric constant (?r)-frequency characteristics, when the value of excess Bi content in precursor sols is 10%. In detail, its remnant polarization (2Pr) value is 40 μC/cm2, the capacitance tunability is 21% measured at room temperature under conditions of an applied voltage of 8 V and measurement frequency of 10 kHz, and the ?r is 696 at 100 kHz frequency. 相似文献
14.
We have grown lead iron niobate thin films with composition Pb(Fe1/2Nb1/2)O3 (PFN) on (0 0 1) SrTiO3 substrates by pulsed laser deposition. The influence of the deposition conditions on the phase purity was studied. Due to similar thermodynamic stability spaces, a pyrochlore phase often coexists with the PFN perovskite phase. By optimizing the kinetic parameters, we succeeded in identifying a deposition window which resulted in epitaxial perovskite-phase PFN thin films with no identifiable trace of impurity phases appearing in the X-ray diffractograms. PFN films having thicknesses between 20 and 200 nm were smooth and epitaxially oriented with the substrate and as demonstrated by RHEED streaks which were aligned with the substrate axes. X-ray diffraction showed that the films were completely c-axis oriented and of excellent crystalline quality with low mosaicity (X-ray rocking curve FWHM?0.09°). The surface roughness of thin films was also investigated by atomic force microscopy. The root-mean-square roughness varies between 0.9 nm for 50-nm-thick films to 16 nm for 100-nm-thick films. We also observe a correlation between grain size, surface roughness and film thickness. 相似文献
15.
At room temperature deposited Ge films (thickness < 3 nm) homogeneously wet CaF2/Si(1 1 1). The films are crystalline but exhibit granular structure. The grain size decreases with increasing film thickness. The quality of the homogeneous films is improved by annealing up to 200 °C. Ge films break up into islands if higher annealing temperatures are used as demonstrated combining spot profile analysis low energy electron diffraction (SPA-LEED) with auger electron spectroscopy (AES). Annealing up to 600 °C reduces the lateral size of the Ge islands while the surface fraction covered by Ge islands is constant. The CaF2 film is decomposed if higher annealing temperatures are used. This effect is probably due to the formation of GeFx complexes which desorb at these temperatures. 相似文献
16.
Changzheng Wang Yiqing Zhang Peiming Zhang Yonghua Rong T.Y. Hsu 《Journal of magnetism and magnetic materials》2008
A series of FeCo–SiO2 nanogranular films were prepared using magnetron controlled sputtering method. The microstructure, tunneling giant magnetoresistance (TMR) and magnetic properties of FeCo–SiO2 films deposited at room temperature and then annealed at various temperatures were investigated using transmission electron microscopy (TEM), conventional four probes method and vibrated sample magnetometer (VSM) under room temperature, respectively. The results showed that all FeCo–SiO2 films consisted of FeCo granules with equiaxial shape uniformly dispersed in the SiO2 matrix and formed body-centered cubic (bcc) structure. With increasing the annealing temperature, FeCo granule size increased monotonically. For film with 30.5 vol% FeCo, the size distribution satisfied the log-normal function at lower annealing temperature. While with increasing annealing temperature, the size distribution deviated gradually from the log-normal function. Meanwhile, upon varying the annealing temperature, the TMR of films with lower volume fraction reached a peak value at higher annealing temperature and the TMR of films with higher volume fraction reached a peak value at lower annealing temperature. In addition, the results also indicated that the sensitivity of TMR changed non-monotonically with the increment of the annealing temperature and both the saturation magnetization and the susceptibility of FeCo (30.5 vol%)–SiO2 films increased with increasing the annealing temperature. 相似文献
17.
A. Javed N.A. Morley M.R.J. Gibbs 《Journal of magnetism and magnetic materials》2009,321(18):2877-2882
Polycrystalline Fe100−xGax (19?x?23) films were grown on Si(1 0 0) substrates at different partial pressures of sputtering gas ranging from 3 to 7 μbar. Microstructural, magnetic and magnetostrictive properties were studied using X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS) and magneto-optic Kerr effect (MOKE) magnetometry respectively. X-ray diffraction showed that all films have the body-centered cubic (bcc) Fe-Ga phase with the 〈1 1 0〉 direction out of the film plane. Magnetic characterization of the films showed that the films prepared at 3 μbar had weak uniaxial anisotropy whereas films grown at Ar pressures in the range 4-7 μbar were magnetically isotropic. The effective saturation magnetostriction constants (λeff) of the films were measured using the Villari effect. It was found that effective saturation magnetostriction constants were almost constant over the Ga composition range achieved by varying the sputtering pressure. The measured effective magnetostriction constants fit closely to the calculated saturation magnetostriction constants of 〈1 1 0〉 textured polycrystalline films with the 〈1 1 0〉 directions slightly canted with respect to the normal to the sample surface. It was found that a high pressure of the sputtering gas effected the magnetic softness of the films. The saturation field increased and remanence ratio decreased with increase in pressure. 相似文献
18.
B.S.D.Ch.S. Varaprasad A. RajanikanthY.K. Takahashi K. Hono 《Journal of magnetism and magnetic materials》2011,323(23):3092-3097
Co2MnGa0.5Sn0.5 (CMGS) thin films were epitaxially grown on MgO (0 0 1) substrates by magnetron sputtering and the current spin polarizations of the films with different post annealing conditions were measured by the point contact Andreev reflection method. The film deposited at a substrate temperature of 150 °C had a B2 structure and its spin polarization was estimated to be 59%. The film was ordered to the L21 structure by annealing at 600 °C, and the spin polarization was enhanced to 66%. The spin polarization and the intensity of the L21 diffraction showed clear correlation, suggesting L21 ordering is essential to achieve higher spin polarization of this quaternary Heusler alloy. 相似文献
19.
The Sm2Co17-based intermetallic films with additives of Fe, Cu, and Zr have been deposited on Si(1 0 0) substrates by dc magnetron sputtering process. Subsequent thermal treatment and the film thickness are found to have significant contribution to the crystal structure and grain structure, which determines the magnetization reversal process and intrinsic coercivity (HC) of these films. The conventional thermal annealing (CTA) treatment almost failed to crystallize the as-deposited films, leading to a very low HC. Continuous and homogeneous domain walls cannot form in this deteriorated microstructure, so that the pinning mechanism can be excluded. Contrarily, the films with thickness exceeding 0.8 μm treated by rapid recurrent thermal annealing (RRTA) show an improved HC, which is attributed to the observed completed crystallization and compact microstructure. It is suggested that this film structure is responsible for providing continuous and homogeneous domain walls, leading to a magnetization reversal process controlled by domain wall pinning model. In special, the HC of the RRTA-treated film with thickness of 1.8 μm shows a good temperature dependence from 25 to 300 °C, with intrinsic coercivity temperature coefficient β of −0.23%/°C. 相似文献
20.
S. Bobby Singh H.B. Sharma H.N.K. Sarma Sumitra Phanjoubam 《Physica B: Condensed Matter》2008,403(17):2678-2683
Ferroelectric barium strontium titanate (Ba0.7Sr0.3TiO3)(BST) thin films have been prepared from barium 2-ethylhexanoate [Ba[CH3(CH2)3CH(C2H5)CO2]2], strontium 2-ethylhexanoate [Sr[CH3(CH2)3CH(C2H5)CO2]2] and titanium(IV) isopropoxide [TiOCH(CH3)2]4 precursors using a modified sol-gel technique. The precursor except [TiOCH(CH3)2]4 were synthesized in the laboratory. Transparent and crack-free films were fabricated on pre-cleaned quartz substrates by spin coating. The structural and optical properties of films annealed at different temperatures have been investigated. The as-fired films were found to be amorphous that crystallized to the tetragonal phase after annealing at 550 °C for 1 h in air. The lattice constants “a” and “c” were found to be 3.974 A and 3.990 A, respectively. The grain sizes of the films annealed at 450, 500 and 550 °C were found to be 30.8, 36.0 and 39.8 nm respectively. The amorphous film showed very high transparency (∼95%), which decreases slightly after crystallization (∼90%). The band gap and refractive index of the amorphous and crystalline films were estimated. The optical dispersion data are also analyzed in the light of the single oscillator model and are discussed. 相似文献