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The magnetic properties for monatomic layer (ML)-controlled Co/Ni epitaxial multilayers were investigated in order to evaluate the interface magnetic anisotropy energy (Ks) between Ni and Co layers. The Co/Ni epitaxial multilayers were prepared on an Al2O3 (11-20) substrate with V/Au buffer layers. The value of Ks was definitely larger than that for the textured Co/Ni grown on a thermally oxidized Si substrate. We consider that the sharp interface for the epitaxial Co/Ni played a role to increase the value of Ks, which also enabled us to obtain perpendicular magnetization even for the 1 ML-Co/1 ML-Ni multilayer. [ABSTRACT FROM AUTHOR]

This article reports lattice deformation and phase transition of AlScN thin films in the whole composition. AlScN films were deposited on Pt/Ta/SiO2/Si substrates by direct current magnetron reactive sputtering with Al and Sc targets. At Sc concentration up to 30%, AlScN has a wurtzite structure with piezoelectricity. Transition from a wurtzite phase to a two-phase mixture happens between 30% and 35% Sc concentration, and transition from a two-phase mixture to a cubic phase happens between 38% and 43% Sc concentration. The wurtzite structure gradually deforms with the decrease in lattice constant c from 16% to 35% Sc concentration. Lattice constant c at 38% Sc in the two-phase mixture region is larger than that of 35% Sc concentration. These increases mean that distortion of c axis for the wurtzite structure over 35% Sc concentration in the two-phase mixture region is considered to be released and/or eased due to the appearance of the cubic phase, and that Sc concentration of the wurtzite phase to be smaller and that of the cubic phase larger than the film composition measured by energy-dispersive x-ray spectroscopy and Rutherford backscattering spectroscopy. At higher Sc concentration up to 43%, the remained wurtzite phases are replaced by non-piezoelectric cubic phases, and the cubic structure approaches the rock-salt structure of ScN with a further increase in Sc concentration. [ABSTRACT FROM AUTHOR]

We present a simple method to determine the linear electro-optic coefficient of thin films with spectroscopic ellipsometry. This technique allows noncontact and nondestructive measurement of the as-grown state of films without the need to fabricate a waveguide. The principle behind this is that the electro-optic effect is regarded as perturbation to the optical parameters. Comparing differences in tan Ψ spectra in terms of applied voltage and wavelength yields a change in the effective wavelength of light propagating through a dielectric medium, which is equivalent to electro-optic-induced phase shift. We demonstrate the feasibility of this procedure to determine the Pockels coefficient (r33) of a preferentially c-axis-oriented LiNbO3 film on a Si(100) substrate. Dispersion of effective r33 values at wavelengths between 0.3 and 0.8 μm was obtained. [ABSTRACT FROM AUTHOR]

Tantalum disulfide has been attracting considerable attention due to its rich phase diagram that includes polytypes and charge density waves, thus having potential for electrical device applications. However, epitaxial TaS2 thin films grown by chemical vapour deposition are still limited due to few available precursors. Herein, an originally designed atmospheric chemical vapour deposition with a separate-flow system was proposed to accomplish the controlled synthesis of TaS2 thin films. The sophisticated deposition sequence enables us to make unidirectional TaS2 triangle domains on c-plane sapphire using a chloride precursor. The quality of the grown TaS2 thin films was confirmed by X-ray diffraction, Raman spectroscopy, transmission electron microscopy and observing a step-and-terrace structure without spiral defects. The growth mechanism was discussed and concluded as the Volmer–Weber mode from the surface morphologies and elemental analysis. Our strategy is expandable to the other transition metal dichalcogenides because all the chloride precursors show a considerable vapour pressure below 200 °C. [ABSTRACT FROM AUTHOR]

Manipulation of topological structures has become one of the most interesting topics in ferroelectrics through multiple excitations due to their prospective applications in electro-mechanical-optic devices. Scanning probe microscopy (SPM) has been developed as a powerful tool to manipulate the polar state in ferroic materials, in which the electric field induced by charged SPM enables dynamic coupling between the switching of the polar states and electromigration of oxygen vacancies, resulting in unknown influences of oxygen vacancy on the polar state in ferroelectric topological structures. Here, we regulate the polar state by considering oxygen vacancies and a non-uniform electric field under the charged SPM experiment for flux-closure domain structures in PbTiO3 thin films. The charged SPM probe can excite the growth of newly flux-closure domains to improve the density of topological states. In contrast, oxygen vacancies are found to suddenly prohibit the evolution of the flux-closure domain structure, when their concentration jumps to a threshold value. Our results might give guidelines to increase and stabilize the memory unit through co-modulating the electric field and ions injection in the information field. [ABSTRACT FROM AUTHOR]

The development of thin-film photovoltaics has emerged as a promising solution to the global energy crisis within the field of solar cell technology. However, transitioning from laboratory scale to large-area solar cells requires precise and high-quality scribes to achieve the required voltage and reduce ohmic losses. Laser scribing has shown great potential in preserving efficiency by minimizing the drop in geometrical fill factor, resistive losses, and shunt formation. However, due to the laser induced photothermal effects, various defects can initiate and impact the quality of scribed grooves and weaken the module's efficiency. In this regard, much research has been conducted to analyze the geometrical fill factor, surface integrity, and electrical performance of the laser scribes to reach higher power conversion efficiencies. This comprehensive review of laser scribing of photovoltaic solar thin films pivots on scribe quality and analyzes the critical factors and challenges affecting the efficiency and reliability of the scribing process. This review also covers the latest developments in using laser systems, parameters, and techniques for patterning various types of solar thin films to identify the optimized laser ablation condition. Furthermore, potential research directions for future investigations at improving the quality and performance of thin film laser scribing are suggested. [ABSTRACT FROM AUTHOR]

We investigated the microstructures and electrical properties of Nd(Zn0.5Ti0.5)O3 thin films fabricated using the sol--gel method at various preheating temperatures and annealing temperatures. The composites and their morphological characteristics were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) and were found to be sensitive to both the preheating temperature (100-300 °C) and annealing temperature (600-800 °C). The diffraction pattern indicated that the deposited films exhibit a polycrystalline microstructure. The dielectric constant and leakage current density of the Nd(Zn0.5Ti0.5)O3 thin films at a preheating temperature of 300 °C and an annealing temperature of 700 °C were 16 and 2.13 × 10-8, respectively. The experimental data for Nd(Zn0.5Ti0.5)O3 thin films can be applied to wireless communication microwave components, such as temperature-sensing antennas. [ABSTRACT FROM AUTHOR]

We investigate the frequency dispersion of complex permeability in the GHz range in superparamagnetic nickel–zinc ferrite thin films with different Ni/Zn ratios using a microstrip probe. The films, comprising crystallites as small as 3 nm and deposited by a microwave-irradiation-assisted solvothermal method, exhibit the coexistence of two resonance characteristics—a ferromagnetic resonance peak ( f r ) at ∼2 GHz and a superparamagnetic resonance peak ( f b ) above 20 GHz, breaching Snoek's limit. The high value of f r is attributed to the high surface anisotropy and far-from-equilibrium distribution of cations in the lattice, while f b is attributed to the thermally driven superparamagnetic relaxation of ferrite nanocrystallites in the thin films. This work demonstrates the feasibility of employing superparamagnetic ferrite thin films so deposited as excellent CMOS-integrable magnetic components for high-speed and high-frequency electromagnetic device applications. [ABSTRACT FROM AUTHOR]

We have fabricated (Pr1-yYy)1-xCaxCoO3 (PYCCO) epitaxial films with various thicknesses by pulsed laser deposition on the SrLaAlO4 (SLAO) substrate that applied an in-plane compressive stress to the film, and investigated the temperature dependence of the electrical resistivity, ρ(T), of the films. An anomalous ρ (T) upturn with a broad hysteresis could be clearly observed only for the thinnest film (d=50 nm), and the ρ (T) anomaly decreased by increasing film thickness, d. The temperature dependence of the X-ray absorption near-edge structure (XANES) spectra at Pr L2-edge was measured for the films, and the valence states of praseodymium (Pr) ion were determined using the analysis of the XANES spectra. As a result, the average valence of the Pr ion in the d=50 nm film slightly increases with decreasing temperature from the common value of 3.0+ around room temperature to 3.15+ at 8K. The valence shift of Pr is thus similar to what was observed on the PYCCO polycrystalline bulks with an abrupt metal-insulator transition, accompanied by a spinstate (SS) transition of Co ions. Furthermore, the low-temperature SQUID measurements evidenced a paramagnetic behavior down to the lowest temperature, which suggests that the dominant part of Co3+ ions in the film grown on the SLAO substrate tends to be in the low spin state characteristic for the insulating ground state. These results strongly suggest that the anomalous ρ(T) upturn in the thin films on the SrLaAlO4 (SLAO) substrate is closely related to the SS transition of Co ions. On the other hand, PYCCO films grown on the LaAlO3 (LAO) substrate that applied an in-plane tensile stress showed no valence shift of Pr ions and developed a long range ferromagnetic order, which points to a complete suppression of the low-temperature transition. The behaviors of the epitaxial films are discussed in terms of the in-plane stress exerted by different substrates and accumulated elastic energy. [ABSTRACT FROM AUTHOR]

The properties of Fe–Rh–Pd epitaxial thin films grown on MgO(001) were studied as a function of growth temperature. Films grown above 400 ° C exhibit a first-order antiferromagnetic to ferromagnetic magnetic phase transition with a transition temperature that decreases as the growth temperature is increased. The chemical order parameter computed from the ratio of intensities of the (001) and (002) diffraction peaks is nearly independent of the growth temperature, while the lattice constants change slightly. A comparison of our structural, magnetic, and electrical transport results with first-principle-based calculations as well as literature results indicates that the transition temperature of Fe–Rh-based alloy films depends sensitively on the lattice parameters and is of electronic origin. The transition temperature and its width can be tuned over a wide range by controlling the crystal structure via growth conditions or postdeposition annealing. [ABSTRACT FROM AUTHOR]

In response to develop wide-band noise absorbers with an improved low-frequency performance, this study investigates hybrid absorbers that are composed of conductive Fe3O4 thin film and magnetic composite sheets. The Fe3O4 films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ωm. Rubber composites with flaky Fe-Si-Al particles of a high permeability and high permittivity are used as the magnetic sheet functioning as an electromagnetic shield barrier. Microstrip lines with a characteristic impedance of 50 Ω are used to measure the noise absorbing properties. For the Fe3O4 film with a low surface resistance and covered by the magnetic sheet, approximately 80% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or Fe3O4 film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the Fe3O4 film through increased electric field strength bounded by the upper magnetic composite sheet. The noise absorption is further enhanced through increasing the electrical conductivity of the film containing more conductive phase (Fe3O4 + Fe), which can be prepared in a reduced oxygen partial pressure during reactive sputtering. [ABSTRACT FROM AUTHOR]

This high-frequency magnetic properties of 250-nm-thick Co85-(x+y)Zr3+xNb12+y (x: 0-5.5, y: 0-11.0) amorphous films are examined as functions of Zr (x) and Nb (y) concentrations. Both x and y influence the high-frequency magnetic properties. In the case of x<3.0 and y⩽5.0, each permeability spectrum appears, but increasing x and y decreases the ferromagnetic resonance (FMR) frequency from 1.20 GHz to 0.41GHz and increases the effective damping constant from 0.15 to 0.43. For x=3.0 and y=8.2, although the permeability spectrum disappears, the effective damping constant is estimated to be approximately 0.82. In contrast, the high-frequency magnetic properties cannot be obtained for x=5.5 and y=11.0. Hence, appropriately selecting both Zr and Nb concentrations should effectively control the high-frequency magnetic properties. This finding should be of interest from the viewpoint of new thin film applications, such as microscopic electromagnetic compatibility (EMC), in which properly adjusting the permeability and FMR profiles is vital. [ABSTRACT FROM AUTHOR]

Nanocomposites of TiO2 and carbon nanotubes (CNTs) have been extensively studied in photocatalysis, sensing, and energy conversion and storage over the last decade. The unique properties of these nanocomposites are greatly dependent on the morphology, crystallinity, and homogeneity of the TiO2 coating. However, a fine control of the film microstructure is still challenging due to limited understanding of early stages of the TiO2 growth. The presence of an intermediate buffer layer can induce remarkable changes in the morphological and structural characteristics of the coatings. Here, TiO2 films deposited by atomic layer deposition (ALD) on CNTs without and with different intermediate layers (Al2O3 and ZnO) have been systematically investigated. Compared to bare CNTs, it is suggested that these two intermediate layers with higher surface energy can lead to a delay of the TiO2 crystallization, ultimately resulting in the growth of conformal and crystalline TiO2 films. This study demonstrates a strategy to tailor the microstructure and the properties of thin films via ALD by applying intermediate layers and provides information about the role of surface energy of the substrate in crystallization and growth behavior of ALD thin films. [ABSTRACT FROM AUTHOR]

We investigate the relationship between structural parameters, magnetic ordering, and the anomalous Hall effect (AHE) of Mn3+xSn1−x (−0.42 ≤ x ≤ +0.23) thin films annealed at various temperatures Ta. The crystal structure changes with x and Ta, and at Ta ≥ 500 °C near the stoichiometric composition (−0.08 ≤ x ≤ +0.04), epitaxial single-phase D019-Mn3+xSn1−x (10 1 ̄ 0) is obtained. At room temperature, a larger AHE is obtained when the single-phase epitaxial Mn3Sn with the lattice constant closer to that of bulk is formed. The temperature dependence of the AHE shows different behaviors depending on Ta and can be explained by considering the variation of magnetic ordering. A close inspection into the temperature and composition dependence suggests a variation of magnetic phase transition temperature with composition and/or a possible correlation between the AHE and Fermi level position with respect to the Weyl points. Our comprehensive study on (10 1 ̄ 0) -oriented epitaxial Mn3Sn thin films would provide the basis for utilizing the unique functionalities of non-collinear antiferromagnetic materials. [ABSTRACT FROM AUTHOR]

We report the growth and characterization of the Co 0. 2 Fe 0. 8 thin film. The thin film was deposited on Si (100) substrate by using a direct-current magnetron sputtering deposition technique. The Grazing Incidence X-ray Diffraction (GIXRD) analysis suggests a bcc crystal structure with a lattice constant of 2.87 Å. The X-ray reflectivity (XRR) data analysis shows the thickness of the Co 0. 2 Fe 0. 8 thin film is about 30 nm. The Energy Dispersive X-ray (EDAX) analysis shows the presence of 22.94% of Co and 77.06% of Fe in Co 0. 2 Fe 0. 8 thin film. The Magneto-Optic Kerr Effect (MOKE) technique was used to investigate the magnetic properties and results support that Co 0. 2 Fe 0. 8 thin film exhibits soft magnetic character. The analysis of the M–H loop suggests that the value of the coercive field decreases with the increase of angle with respect to the magnetic easy axis. The MOKE measurement suggests that Co 0. 2 Fe 0. 8 thin film alloy exhibits the least anisotropy with two-fold magnetic anisotropy. Magnetization reversibility was observed by using high-resolution Kerr microscopy. The domain images showed that reversibility occurs through nucleation and domain wall motion. Magnetic anisotropy dispersion was also observed which may be due to the misalignment of grains in the film due to which we got the least anisotropy. These properties of the prepared sample found potential application in the field of spintronics and magnetic sensors. [ABSTRACT FROM AUTHOR]

Mn1.4Co1.0Ni0.6O4 (MCN) thin films are prepared by RF sputtering deposition method on amorphous Al2O3 substrate. Microstructure and X-ray photoelectron spectroscopy analyses suggest improvements in crystallinity and stoichiometry for MCN films with post-annealed process. Infrared (IR) optical constants of the MCN films are obtained by IR spectroscopic ellipsometer (SE) in the range of 1500 cm-1 to 3200 cm-1 (2.8-6.7 μm). The derived effective charge supports the increase of the oxidation after annealing. The dielectric function of the films is also extracted by SE in the range of 300-1000 nm adopting a double Lorentz model together with a Tauc-Lorentz model. The mechanism in electronic transition process is discussed based on the variation observed in the optical absorption spectra of the as-grown and post-annealed samples. The optical absorption peaks located at 1.7 eV, 2.4-2.6 eV, and 3.5-4 eV are attributed to the charge-transfer transitions of 2p electrons of oxygen ions and 3d electrons of Mn and Co ions. Our results are very important to understand the optoelectronic mechanism and exploit applications of metal oxides. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the structure and magnetic properties of Ni65Fe28Ga7 films with different thicknesses prepared by magnetron co-sputtering. We found the grain size is less than 8 nm for all films and increases with the thickness. For the thinner films with the thickness lower than the critical value, the effective saturated magnetization is about 8.4 kGs, while the saturated field and coercivity are, respectively, lower than 25 Oe and 15 Oe. The films exhibit good soft magnetic properties and the Gilbert damping increases almost linearly with the thickness. Above the critical thickness, the stripe domains are observed. As the thickness increases further, the stripe domains widen and the rotatable anisotropy strengthens. [ABSTRACT FROM AUTHOR]

The advent of modern thin-film deposition approaches has ushered in a new era of designed materials with well-controlled composition distributions, e.g., compositionally graded ferroelectric (CGFE) thin films, and thereby, it is readily accessible CGFE/FM (ferromagnetic) multilayer thin films. Being recognized this emerging class of materials, in this study, we develop a phase-field model based on the Ginzburg–Landau theory that takes into account the gradient of ferroelectric (FE) compositions in order to predict material properties of CGFE/FM thin films. The developed phase-field model is applied to investigate the effect of the FE composition gradient on magnetoelectric (ME) coupling of graded Pb(1−x)SrxTiO3/CoFe2O4 laminated nanocomposites. Two types of composition gradients are considered: inward (O-type) and outward (X-type) gradients. Unusual polarization domain structures with curved domain walls are formed in CGFE layers, which are governed by the composition gradients and distinct from typical stripe domains in homogeneous counterparts. As a result, the ME effect is strongly dependent on the composition gradient. Particularly, the ME coupling in the O-type nanocomposites increases with the increasing composition gradient, while it decreases in the X-type ones. The dependence of ME coupling on the composition gradient originates from the distinguishable energy distributions in O-type and X-type nanocomposites. This work, therefore, provides a strategy to design the ME effect via the configuration of the composition gradient. [ABSTRACT FROM AUTHOR]

The effects of Ga composition (x) on soft and high-frequency magnetic properties of 10-nm-thick B-doped Fe–Ga (Fe85.1−xGaxB14.9) thin films were investigated. A uniaxial magnetic anisotropy appeared regardless of the Ga composition. The damping constant values and magnetic inhomogeneous broadening at a zero frequency were much lower than those of the Fe–Ga polycrystalline film for all Ga compositions. These results indicate that adding B atoms to Fe–Ga thin films improves the soft and high-frequency magnetic properties of these films and suggest that Fe–Ga–B thin films are candidate magnetostrictive materials for high-frequency devices. [ABSTRACT FROM AUTHOR]

This work reviews some fundamental issues that are relevant for the fabrication of stable‐phase strontium ferromolybdate thin films. The main challenges for strontium ferromolybdate thin film deposition arise from the sensitivity of the material's magnetic properties to point defect formation: i) Antisite defect formation and oxygen nonstoichiometry should be avoided by precise composition control during film manufacturing; ii) a highly ordered state of the correct phase and B‐site cation valence will be obtained only in a very narrow window of growth conditions; iii) to avoid additional antisite disorder with decreasing synthesis temperature, the effective temperature at the film surface should be increased by an energy flux to the growing film surface. Since thin film deposition is nonequilibrium in nature, the review starts with the consideration of equilibrium phase stability. Cation and oxygen stoichiometries are analyzed with regard to their effect on key magnetic properties. Film strain formed due to thermal and lattice mismatch is of great concern since it influences the choice of the substrate. Finally, thin film deposition techniques are valued for their benefits in strontium ferromolybdate thin film technology. [ABSTRACT FROM AUTHOR]

Implementation of the linear electro-optic (EO) effect in thin film waveguides is expected to allow drastic reductions in the drive voltage, power, and dimensions of devices devoted to light modulation. It should also enable the realization of electrically tunable photonic crystal devices. In this paper we introduce a method which eliminates systematically the sources of the unreliability which strongly affects thin film EO characterization. Based on a Fabry-Perot reflective configuration, the method enables characterizing simultaneously the EO, converse-piezoelectric, and electroabsorptive effects in a film. It provides the magnitude and sign of each of the involved coefficients, and allows accounting for the whole of experimental data versus angle of incidence for both transverse-electric and transverse-magnetic polarizations. At λ=633 nm and room temperature, the results obtained with an epitaxial strontium barium niobate (SrxBa1-xNb2O6, x=0.60) ferroelectric thin film, are: r13=+8.5±1.3 pm/V, r33=+38.9±0.5 pm/V, d33=Δe/ΔV=+21±4 pm/V, and Δko/ΔV=(+9.8±0.6)×10-6, where r13 and r33 are two linear EO coefficients, d33 is a converse-piezoelectric coefficient, and e, ko, V represent, respectively, the film thickness, film ordinary extinction coefficient, and applied voltage. Converse-piezoelectric and electroabsorptive effects are found significant in the film response at a frequency below piezoelectric resonance. Diagonal and effective EO coefficients of the (Sr,Ba)Nb2O6 (SBN) film explored in the present work are larger than those of a crystal of lithium niobate (LN) at the same wavelength λ=633 nm. Taking into account the significant difference in dielectric permittivity between the two materials, advances and potential of LN and SBN thin film paths are compared. [ABSTRACT FROM AUTHOR]

For the aim of wide-band noise absorbers with a special design for low frequency performance, this study proposes conductive indium-tin oxide (ITO) thin films as the absorbent materials in microstrip line. ITO thin films were deposited on the polyimide film substrates by rf magnetron cosputtering of In2O3 and Sn targets. The deposited ITO films show a typical value of electrical resistivity (∼10-4 Ω m) and sheet resistance can be controlled in the range of 20–230 Ω by variation in film thickness. Microstrip line with characteristic impedance of 50 Ω was used for determining their noise absorbing properties. It is found that there is an optimum sheet resistance of ITO films for the maximum power absorption. Reflection parameter (S11) is increased with decrease in sheet resistance due to impedance mismatch. On the while, transmission parameter (S21) is decreased with decrease in sheet resistance due to larger Ohmic loss of the ITO films. Experimental results and computational prediction show that the optimum sheet resistance is about 100 Ω. For this film, greater power absorption is predicted in the lower frequency region than ferrite thin films of high magnetic loss, which indicates that Ohmic loss is the predominant loss parameter for power absorption in the low frequency range. [ABSTRACT FROM AUTHOR]

A series of FePtBi/Au multilayers were fabricated by magnetron sputtering. The interfacial microstructure control of Bi and Au atoms and its effect on comprehensive properties of L10-FePt perpendicular films were carefully studied. Results show that: perpendicular magnetic anisotropy of the L10-FePt film can be remarkably enhanced with the epitaxial inducement of Au atoms. On the other hand, intergranular exchange coupling (IEC) of the film is greatly decreased due to the isolation of FePt particles by nonmagnetic Au particles. Moreover, the controllable coercivity of the film can be realized by adjusting ordering degree of the film through diffusion of Bi atoms. Thus, an L10-FePt perpendicular film with controllable coercivity and no IEC is realized with the interfacial microstructure control of surfactant Bi and Au atoms. [ABSTRACT FROM AUTHOR]

The serial films of Mn2.52-xCoxNi0.48O4 (x=0, 0.32, 0.64, and 0.96) with fixed Ni content of 0.48 are prepared on amorphous Al2O3 substrate by chemical solution deposition method. The x-ray diffraction and microstructure analyses indicate that Co/Mn content ratio can modify the preferred crystalline growth direction and the microstructure morphology of different composition is different under the same growth condition. The distribution of the cations for the four compositions is estimated based on the lattice constant and cation radii. The dc resistivity measurements demonstrate our speculation of the cation distributions. The electrical and magnetic measurements show that the thermal activation energy decreases but the ferrimagnetic transition temperature increases with the increase in Co content. The magnetization loop tests indicate that Mn2.52-xCoxNi0.48O4 serial films probably possess magnetic anisotropy with <111> magnetically easy axis. [ABSTRACT FROM AUTHOR]

The present study focuses on the structural and optical properties of ZnO thin films fabricated by sol-gel process and spin coated onto Si (100) and quartz substrates. The ZnO films have a hexagonal wurtzite structure with a grain size of about 50 nm. The x-ray photoelectron spectroscopy measurements reveal the presence of Zn2+ and of zinc hydroxyl groups at the film. Optical properties were studied by photoluminescence (PL) and absorption spectroscopy at low and room temperatures. The absorption spectrum is dominated by a sharp excitonic peak at room and low temperatures. At room temperature, PL observations show two transitions: one near the absorption edge in the ultraviolet (UV) region and the second centered at 640 nm, characteristic of the deep electronic levels in the bandgap. The spectrum at 6 K is dominated by donor bound exciton lines and donor-acceptor pair transitions. LO-phonon replica and two-electron satellite transitions are also observed. These optical characteristics are a signature of good structural quality of the films. [ABSTRACT FROM AUTHOR]

Using spectroscopic ellipsometry electro-optic effect was studied in lead zirconate titanate (PZT) thin films grown epitaxially on Nb-doped SrTiO3(001) substrates by RF magnetron sputtering. A uniaxial multilayer model analysis was applied to extract the linear and quadratic electro-optic coefficients from the shifts in the ordinary and extraordinary refractive indices with electric field applied along the (001) direction. The effective linear and quadratic coefficients were measured as -134.6×10-12 m/V and 8.5×10-18 m2/V2, respectively, at a wavelength of 632.8 nm, while the individual linear electro-optic coefficients r33 and r13 were -157.1 and 22 pm/V, respectively. The existence of the linear electro-optic effect in unpoled PZT films was attributed to the presence of a built-in polarization and simultaneous poling during measurements. [ABSTRACT FROM AUTHOR]

Dielectric and Raman scattering experiments were performed on polycrystalline Pb1-xBaxTiO3 thin films (x=0.40 and 0.60) as a function of temperature. The dielectric study on single phase compositions revealed that a diffuse-type phase transition occurred upon transformation of the cubic paraelectric to the tetragonal ferroelectric phase in all thin films, which showed a broadening of the dielectric peak. Diffusivity was found to increase with increasing barium contents in the composition range under study. In addition, the temperature dependence of Raman scattering spectra was investigated through the ferroelectric phase transition. The temperature dependence of the phonon frequencies was used to characterize the phase transitions. Raman modes persisted above the tetragonal to cubic phase transition temperature, although all optical modes should be Raman inactive. The origin of these modes was interpreted as a breakdown of the local cubic symmetry by chemical disorder. The lack of a well-defined transition temperature and the presence of broadbands in some temperature intervals above the paraferroelectric phase transition temperature suggest a diffuse-type phase transition. [ABSTRACT FROM AUTHOR]

The magnetic properties and microstructure of annealed near-equiatomic FePt thin films with Ta and Ta/Bi buffer layers have been investigated. While Ta buffer layer effectively enhances the coercivity of FePt thin films, the insertion of a thin Bi layer between FePt and Ta layers further boosts the coercivity multifold. Most representatively, the 12 nm Fe48Pt52 films without buffer and with Ta (6 nm), and Ta (6 nm)/Bi (2 nm) buffer layers after annealing at 400 °C have coercivity of 0.95, 2.7, and 9.2 kOe, respectively, indicating greatly promoted L10 ordering of FePt films through a buffer layer of Ta, especially Ta/Bi. Moreover, the intergrain exchange interaction is appreciably reduced for the annealed Ta/FePt film and almost decoupled for the Ta/Bi/FePt film after annealing. The structural and chemical analyses reveal that Pt atoms transfer from FePt layer into the Ta layer while Ta atoms migrate into the grain boundaries of the FePt layer, and the thin Bi insertion layer reinforces the migration of Ta and Pt due to the outdiffusion of Bi during annealing, which results in the improvement of the ordering as well as the weakening of the intergrain exchange coupling for Ta/FePt, especially for Ta/Bi/FePt. [ABSTRACT FROM AUTHOR]

Nanogranular CoAlO thin films were fabricated by rf magnetron sputtering using Co target partially covered by Al2O3 chips in argon atmosphere. The films consist of Co nanograins with a mean diameter of 5–30 nm surrounded by an amorphous Al–O phase. It was found that Co grains of face-centered-cubic and hexagonal-close-packed structures coexist in the films with relatively low (Al,O) content, whereas Co grains of face-centered-cubic structure are preferentially formed in the films with higher (Al,O) content. Due to the microstructure changes with increasing (Al,O) content in the films, coercivity and magnetization decrease but the anisotropy field increases. The high frequency properties of the CoAlO films were experimentally characterized, and the effects of magnetization, anisotropy field, and damping factor on the permeability spectrum are also analyzed using the Landau-Lifshitz-Gilbert equation. The ferromagnetic resonance frequency was found to increase from 2.1 to 2.8 GHz with the microstructure change in the films. [ABSTRACT FROM AUTHOR]

Ta penetration into a planar template-type porous low-k film during atomic layer deposition of TaN has been investigated by evaluating relations between Ta penetration and number of deposition cycles, exposure time of Ta precursor per deposition cycle, substrate temperature, and porosity of the porous low-k. The precursors were pentakisdimethylaminotantalum [PDMAT:Ta(N(CH3)2)5] and NH3. The porous low-k was a methylsiloxane (MSX) whose pore size in the maximum distribution and porosity of the porous low-k were 0–1.9 nm and 0%–47%. Depth profile of the Ta penetration was measured by transmission electron microscopy and energy dispersive x-ray spectroscopy. The amount of penetrated and the penetration depth depended on the porosity. It was found that the precursors penetrate into the MSX film dominantly by gas phase diffusion through pores connecting from the surface to the inside. Increased surface area of the MSX film due to the pores results in a depletion of precursor at the wafer edge, and that this depletion causes the penetration characteristics at the edge of wafer differ from those at the center of the wafer. Moreover, the thickness required for the pore sealing by additive liner deposition is discussed. [ABSTRACT FROM AUTHOR]

Two series of epitaxial CoPt and FePt films, with nominal thicknesses of 42 or 50 nm, were prepared by sputtering onto single-crystal MgO(001) substrates in order to investigate the chemical ordering and the resultant magnetic properties as a function of alloy composition. In the first series, the film composition was kept constant, while the substrate temperature was increased from 144 to 704 °C. In the second series the substrate temperature was kept constant at 704 °C for CoPt and 620 °C for FePt, while the alloy stoichiometry was varied in the nominal range of 40–60-at. % Co(Fe). Film compositions and thicknesses were measured via Rutherford backscattering spectrometry. The lattice and long-range order parameter for the L10 phase were obtained for both sets of films using x-ray diffraction. The room-temperature magnetocrystalline anisotropy constants were determined for a subset of the films using torque magnetometry. The order parameter was found to increase with increasing temperature, with ordering occurring more readily in FePt when compared with CoPt. A perpendicular anisotropy developed in CoPt for substrate temperatures above 534 °C and in FePt above 321 °C. The structure and width of the magnetic domains in CoPt and FePt, as seen by magnetic force microscopy, also demonstrated an increase in magnetic anisotropy with increasing temperature. For the films deposited at the highest temperatures (704 °C for CoPt and 620 °C for FePt), the order parameter reached a maximum near the equiatomic composition, whereas the magnetocrystalline anisotropy increased as the concentration of Co or Fe was increased from below to slightly above the equiatomic composition. It is concluded that nonstoichiometric L10 CoPt and FePt, with a slight excess of Co or Fe, are preferable for applications requiring the highest anisotropies. [ABSTRACT FROM AUTHOR]

The crystal structure, microstructure, and magnetic properties for a series of Cu/FePt bilayer films were investigated. The samples were prepared by depositing a Cu top layer on a highly ordered L10 FePt film. To promote interdiffusion, the bilayer samples were annealed at a temperature Td ranging from 300 to 800 °C. X-ray diffraction data indicate that observable diffusion occurs at 400 °C. The maximum coercivity thus obtained is 14.0 kOe, which is 24% larger than that of the ordered FePt film without a Cu top layer. The high Hc can be attributed to the diffusion of copper atoms through the grain boundaries of the magnetic films, which may produce extra pinning sites for domain-wall movement. The ΔM data measured from the Henkel plots of annealed Cu/FePt films change from negative to positive values as Td is raised from 400 to 800 °C. This can result from the effects of demagnetization coupling and exchange coupling and is further explained from the variation of squareness ratios of hysteresis loops. [ABSTRACT FROM AUTHOR]

We have carried out dielectric and Raman spectroscopy studies at the 298-623 K temperature range in polycrystalline Pb0.70Sr0.30TiO3 thin films grown by a soft chemical method. The diffuse phase-transition behavior of the thin films was observed by means of the dielectric constant versus temperature curves, which show a broad peak. Such behavior was confirmed later by Raman spectroscopy measurements up to 823 K, indicating that a diffuselike phase transition takes place at around 548-573 K. The damping factor of the E( 1 TO) soft mode was calculated using the damped simple harmonic oscillator model. On the other hand, Raman modes persist above the tetragonal to cubic phase transition temperature although all optical modes should be Raman inactive. The origin of these modes was interpreted in terms of a breakdown of the microscopic local cubic symmetry by chemical disorder. The lack of a well-defined transition temperature and the presence of broad bands at some temperature interval above the ferroelectric-paraelectric phase-transition temperature suggested a diffuse nature of the phase transition. This result corroborates the dielectric constant versus temperature data, which showed a broad ferroelectric phase transition in this thin film. [ABSTRACT FROM AUTHOR]

The magnetic properties of Fe38Pt62 and Fe52Pt48 films sputter deposited on MgO (001) substrates with and without a buffer layer at the substrate temperature Ts, of 300°C have been investigated. Pt, Au, and PtAu alloys with different compositions were used as the buffer layer to study the influence of the lattice mismatch between the FePt layer and the buffer layer. The L 10 ordered structure with large perpendicular magnetic anisotropy has been obtained for the Fe38Pt62 films irrespective of the buffer layer. The degree of long-range order S and uniaxial magnetic anisotropy energy Ku increase with increasing the lattice mismatch, and S and Ku show maxima of 0.8±0.1 and 2.7 × 107 erg/cm³, respectively, for the film without a buffer layer. For Fe52Pt48 films, on the other hand, the L 10 ordered structure with perpendicular magnetic anisotropy has been obtained only for the film with an Au buffer layer. [ABSTRACT FROM AUTHOR]

We have investigated the size effect of A1→L1[sub 0] ordering of FePt nanoparticles in FePt–Al[sub 2]O[sub 3] granular and FePt/SiO[sub 2] particulate films by transmission electron microscopy (TEM). The TEM results have shown convincingly that ordering does not progress when the particle size has a diameter of less than 4 nm. Calculation of the order parameter profile from the surface to the volume of the FePt nanoparticles based on diffuse-interface theory justified the experimentally observed size dependence of the ordering. The transition length from disorder to order depends on the interfacial energy, hence the critical particle size of ordering should vary depending on the type of matrix and substrate. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Room-temperature x-ray diffraction and Mössbauer effect techniques have been used to characterize the structural features and local atomic environments of sputtered Fe[sub 51]Pt[sub 49] thin films following various isothermal treatments. Both techniques show that no significant changes occur in the chemically ordered L1[sub 0] tetragonal phase after it has formed. In contrast, changes in the disordered face-centered-cubic (fcc) phase are observed prior to the transformation into the ordered tetragonal phase. Mössbauer measurements indicate the development of increasing short-range order in the disordered fcc phase with increasing annealing temperature. Asymmetries in the fcc x-ray diffraction profiles also suggest the presence of lattice distortions caused by atomic size differences commonly found in the quenched disordered fcc phase of materials that form ordered structures. Quasi-real-time kinetic measurements of the disorder→order transformation in sputtered Fe[sub 51]Pt[sub 49] thin films within the temperature range 300 °C≤T≤400 °C have also been conducted using high-temperature x-ray diffraction techniques. Significant differences are observed between the kinetic parameters determined in this study and those of previous reports. It is proposed that these differences arise from the lower temperature range investigated in the present work, where the gradual changes occurring in the fcc phase can influence the rate of the ordering transformation. Furthermore, because the initial state of disorder in Fe[sub ∼50]Pt[sub ∼50] films can be influenced by the deposition conditions, variability in the low-temperature ordering kinetics should be expected among Fe[sub ∼50]Pt[sub ∼50] films prepared under different conditions. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The effect of high magnetic field on the microstructure and magnetic properties of α[sup ′]-FeN films has been studied. The application of a high magnetic field during sputter deposition has a significant influence on the microstructure of α[sup ′]-FeN films. In particular, the grain growth and the surface roughness are suppressed, and concurrently the coercivity becomes much lower. α[sup ′]-FeN films deposited in magnetic fields of 2 and 4 T exhibit smooth surfaces with root-mean-square (rms) roughness of, respectively, 0.38–1.53 nm, saturation magnetization of 2.25–2.32 T and coercivity of 1.6–2.6 kA/m, while α[sup ′]-FeN films deposited at H=0 T show rough surfaces with rms roughness of 6.0–6.8 nm, saturation magnetization of 2.13–2.15 T and coercivity of 9.8–12 kA/m. This effect of high magnetic field on the surface morphology is expected to be widely used to improve various properties of thin films. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A systematic investigation was carried out on the Fe-Co-N thin films with varying Permalloy underlayer thicknesses (in short Py\Fe-Co-N films), which show significantly improved magnetic softness when a very thin Permalloy underlayer is applied. The easy axis coercivities of the Py\FeCo-N films drop from 1.3 kA/m (16 Oe) to 640 A/m (8 Oe) with an appropriate Permalloy underlayer; and the corresponding hard axis coercivity drops from 320 A/m (4 Oe) to less than 80 A/m (1 Oe). The highest transverse permeability is observed in the Py\Fe-Co-N film with a Permalloy underlayer of 3.5 nm, which also shows the smallest dispersion angle α[sub 50] among the Py\Fe-Co-N films. The changes in the mean grain size, texture, and magnetostriction are determined to not be responsible for the observed magnetic softness in the Py\Fe-Co-N films. In contrast, a tantalum underlayer does not reduce the coercivities and dispersion angles in the Ta\FeCo-N films. Based on these results, an exchange-induced ripple reduction mechanism is proposed to explain the effects of the Permalloy underlayer on the Py\Fe-Co-N films. [ABSTRACT FROM AUTHOR]

FeNiN films with 0–56 at % Ni concentrations were prepared by dual ion beam sputtering in a nitrogen–argon gas mixture. Effects of nitrogen and nickel concentrations on the structure and magnetic properties of FeNiN films have been studied. FeNiN films with lower nickel and nitrogen concentrations contained the bcc α-(FeNi) phase, films with 8–12 at % nitrogen and 5–25 at % Ni concentrations contained α[sup ″]-(Fe, Ni)[sub 16]N[sub 2] and γ[sup ′]-(Fe, Ni)[sub 4]N phases, and films with 30–56 at % Ni concentrations consisted of a mixture of fcc γ-FeNi alloy and γ[sup ′]-(Fe, Ni)[sub 4]N phases. The FeNiN films with 8–12 at % nitrogen and 5–15 at % nickel concentrations showed high saturation magnetization of 2.2–2.3 T and low coercivity of 96–110 A/m. The variation of the magnetic properties was attributed to the change in the structure of the films. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Thin films of different metals M (M=Ti, Zr, Hf, Nb, Fe, and Ni) of thickness around 10 nm are deposited on Si(100) substrates and a ∼30 nm Co film is deposited on these metal films using the magnetron sputtering method. Cross-sectional transmission electron microscopy (XTEM) shows the presence of a ∼2 nm buried ultrathin amorphous interlayer at the interface between the Co layer and the M layers (M=Ti, Zr, Hf, and Nb). X-ray reflectivity is used to determine the electron density of this buried ultrathin amorphous interlayer. X-ray diffraction (XRD) is used to determine the crystalline quality of the deposited Co film on these various metal film substrates. The XRD peaks of Co(111) and Co(222) are observed when Ti, Zr, Hf, and Nb are used as substrates. Pole figure measurements confirm that the Co film is highly textured on such metallic substrates. On the other hand no characteristic XRD peaks of cobalt are observed when Ni and Fe are used as the substrate, howe! ver, XTEM shows the presence of the Co film on those substrates. Theoretically, the heat of mixing (-ΔH) has been calculated for Co-M systems. The local temperature rise is estimated using the average heat capacity and the calculated heat of mixing of the amorphous interface compound (Co[sub 3]M). The local temperature rise due to the amorphous phase formation and hence better mobility of the further deposited metal atoms is the cause of highly textured Co thin films on such metal substrates. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies the effect of polyatomic ion structure on thin-film growth by experiments and molecular dynamics simulations. Polyatomic ion-surface modification; Role of polyatomic ions in plasma-surface modification; Hydrocarbon analogs of the fluorocarbon species.

Studies the particle generation by gas-phase nucleation in the plasma enhanced chemical vapor deposition process and its effects on thin film surface morphology for a conventional radio frequency plasma reactor. Observation of the particles suspended in the plasma space and deposited on the film by in situ laser light scattering methods.

Materials with perpendicular magnetic anisotropy (PMA) have been intensively studied for high-density nonvolatile memory such as spin-transfer-torque magnetic random access memory with low switching current density and high thermal stability. Compared with crystalline PMA multilayers, considerable works have been done on amorphous PMA multilayers because the amorphous materials are expected to have lower pinning site density as well as smaller domain wall width. This study is an overview of the PMA properties of amorphous [CoSiB/Pt]N multilayers with varying N, where the energy contribution is changed from domain wall energy to magnetostatic energy around N=6. By measuring the field-induced domain wall motion, we obtain the creep exponent of μ=1/4. These results in the amorphous PMA multilayers of [CoSiB/Pt]N demonstrate possible potential as a free layer for PMA-based memory devices. [ABSTRACT FROM AUTHOR]

Presents information on a study which analyzed the implantation of iron ions into a thermally grown silica film using x-ray diffraction method. Research design and methodology; Results and discussion; Conclusions.

The Mn-Ge binary system has been intensively studied because of a variety of phases with intriguing magnetic properties. Here, we report the thin film fabrication of two types of Mn3Ge by employing Pt and Ru seed layers. Our structural analysis, in addition to magnetic and transport measurements, have revealed that the Mn3Ge film with the Pt layer has γ-Mn type cubic structure. This is in contrast to the Mn3Ge film with Ru seed layer, which posseses D022 tetragonal structure. Pt/Mn3Ge also exhibits antiferromagnetic properties, including the exchange bias effect with the blocking temperature of TB ∼ 350 K. [ABSTRACT FROM AUTHOR]

Discusses a study that investigated the microstructure and magnetism in nanocrystalline films. Description of the microstructure of the films; Details on the evolution and nitrogen incorporatiion of the film; Experimental method and result of the study.

Provides information on a study which investigated the structure and properties of cobalt-based films prepared by radio frequency magnetron sputtering using nitrogen or oxygen and argon gases. Methods; Results; Discussion.

Presents a study that measured the average magnetic moment per iron atom for a single-phase Fe[sub16]N[sub2] film by using a vibrating sample magnetometer and Rutherford scattering. Temperature dependence of the resistivity; Anomalous Hall resistivity for Fe[sub16]N[sub2]; G Factor for Fe[sub16]N[sub2].

Deals with a study which analyzed the dynamic behavior of the magnetization for (111)-oriented films with cubic crystalline structures. Theoretical background; Sample preparation and measurements; Experimental results; Conclusion.

Reports on the preparation of amorphous Co[sub0.95-x]Zr[sub5]M[subx] and (Co[sub91-x]Pt[subx])Zr[sub9] thin films by radio-frequency sputtering. Experimental procedure; Results and discussion.