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The evolution of hysteresis and magnetoresistive properties of exchange-coupled Fe20Ni80/Tb–Co bilayers with modified interface was investigated in the temperature range from 79 to 450 K. Exchange bias field was shown to decrease monotonously with increasing temperature, demonstrating a very similar behavior for unmodified films and samples with ultrathin Ti spacer or selectively annealed permalloy layer. The observed dependence, therefore, is mostly attributed to the changes of the Tb–Co layer’s magnetization and magnetic anisotropy. Anisotropic magnetoresistance (AMR) value measured on all samples shown typical for the permalloy alloy reduction at higher temperatures regardless of the sample’s type. A simultaneous decrease of the exchange bias field and the value of the AMR effect was shown to open the possibility for the compensation of the temperature dependence of the medium’s response to the application of the external magnetic field. [ABSTRACT FROM AUTHOR]

In this study, the thermal stability of the in-plane uniaxial anisotropy field of Fe32Co44Hf12N12/Ti50N50 multilayer films was investigated from room temperature up to 500^\circC with regard to contactless high-frequency sensor applications. The uniaxial anisotropy field of about \mu0Hu\approx 5\ mT was thermally induced by annealing the films in a static magnetic field of 50 mT in vacuum for one hour either at an annealing temperature of Ta=400^{\circ}C or Ta=600^{\circ}C. The films which were annealed at Ta=600^{\circ}C show a clear distinction between the easy and hard axis of polarization up to temperatures of 500^\circC. Hence, the uniaxial anisotropy, thermally induced at Ta=600^{\circ}C, is stable at working temperatures up to 500^\circC. In contrast, films with a uniaxial anisotropy induced at Ta=400^{\circ}C show a different behavior. Here, hysteresis loop measurements indicate that above a working temperature of 200^\circC the uniaxial anisotropy field turns away from its direction at room temperature. In conclusion, only the Fe32Co44Hf12N12/Ti50N50 multilayer films with a uniaxial anisotropy field induced at Ta=600^{\circ}C promise a great potential for contactless high-frequency sensor applications up to 500^\circC. [ABSTRACT FROM AUTHOR]

The magnetic and structural properties of atomic-scale [Fe/Pt]18 and [Fe/Pt/Ag]18 multilayer films annealed at 350 and 400°C have been investigated. The results indicate that, by introducing thin Ag addition layers, the ordering temperature of FePt with nominal 7.4-nm thickness (excluding Ag thickness) can be significantly reduced to 350°C, at which a relatively large coercivity is achieved. When annealing temperature increases to 400°C, the atomic-scale [Fe/Pt]18 and [Fe/Pt/Ag]18 multilayer films show (001) orientation. The reduced diffusion length of atoms in atomic-scale multilayer films and an enhanced atomic diffusion coefficient produced by Ag doping led to the low-temperature ordering and (001) orientation of L10 FePt phase. [ABSTRACT FROM AUTHOR]

Results of domain structures observation of individual Ni80 Fe20 and Co sublayers in sputter deposited (NIFe/Au/Co/Au)io multilayers, using an element-sensitive method: the photoemission electron microscopy combined with soft X-ray magnetic circular dichroism, are presented. Also, overall domain structures were studied with magnetic force microscopy. The studies allowed us to reveal submicron stripe domains in the investigated samples and the replication of the stripe domains from the Co layers with perpendicular anisotropy to the NiFe layers with easy-plane anisotropy. [ABSTRACT FROM AUTHOR]

The irreversibility temperatures were measured for a-axis oriented and c-axis in-plane aligned Y123/Pr123 multilayer films in various magnetic fields. Pr123 layers act as two-dimensional (planer) c-axis correlated artificial pinning centers (APCs) in the multilayer films. In the irreversibility field -temperature (Birr T) curves, the crossover was observed near matching field Bφ, for the multilayer films, when the magnetic fields were applied parallel to the c-axis of the film (B//c). It is suggested the vortex state in Y123 films with two-dimensional APCs is Bose glass below the crossover field. The Birr T curves under B//a shifted toward lower temperature and magnetic field regions. [ABSTRACT FROM AUTHOR]

Magnetic properties of FeCoSI/native-oxide multilayer films, prepared by DC magnetron sputtering and exposure to oxygen in a sequence, have been investigated. It is found that the appropriate thicknesses of the native-oxide layers and FeCoSi layers are very important in decreasing coercivity H[subc] of the multilayered films, which may be caused by the exchange coupling between the FeCoSi particles through the oxide. A minimum H[subc] value of 8.4 Oe was obtained for the [FeCoSi (20 A)/native-oxide]50 multilayer film with the largest in-plane uniaxial anisotropy field 11k of 130 Oe. The real part μ' of complex permeability of this sample is more than 100 and flattens almost to 2.5 GHz, while the imaginary part μ" is less than 50 for f < 2.5 GHz. The ferromagnetic resonance frequency is as high as 3.9 GHz, implying that the film is promising for high-frequency applications. [ABSTRACT FROM AUTHOR]

The influence of the Co layer thickness as well as the number of repetitions N on the magnetic properties of (Co/Au)N multilayers was investigated systematically using magneto-optical techniques, vibrating sample magnetometry, and magnetic force microscopy. The studies focused on the characteristics of magnetic hysteresis loops in connection with magnetic domain structure parameters. Increasing the repetitions number, an out-of-plane magnetization ordering is created for Co layers with a thickness larger than the single-layer thickness at which the spin reorientation transition occurs. [ABSTRACT FROM AUTHOR]

Various multilayer amorphous carbon films were prepared by a double bend filtered cathodic vacuum arc system in conjunction with a substrate voltage pulse bias generator. The internal structure of the multilayer films consisted of equal layers of high content (80%) films interspaced periodically (and uniformly) between layers of moderate content (60%) films. The modulation of the multilayer films was systematically varied so as to achieve films of different internal composition for comparative studies. The set of films were further annealed for thermal stability measurements. Properties measured included reduced modulus and stress. Free-standing microcantilevers have also been subsequently fabricated using the various different types of multilayer film using standard lithography and wet etching. The resonance frequencies of the microcantilevers were then measured by a vacuum laser vibrometer setup. [ABSTRACT FROM PUBLISHER]

In the Langmuir-Blodgett (LB) technique, a monolayer on the water surface is transferred onto a substrate, which is raised and dipped through the surface. From this, multilayers can be obtained in which constituent molecules are periodically arranged. The LB technique has attracted considerable interest in the fabrication of electrical and electronic devices. Many researchers have investigated the electrical properties of monolayer and multiplayer films. Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched tree-like structure. Multiple branching yields a large number of chain ends that distinguish dendrimers from conventional star-like polymers and microgels. The azobenzene dendrimer is one of the dendritic macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. [ABSTRACT FROM PUBLISHER]

The assembly of multilayer films of gelatin onto glass substrates using layer-by-layer and lift-off (LbL-LO) technology to modify the surface topography and chemistry properties of in vitro cell culture scaffolds is described. The ability to generate such nanoscale systems containing cell-adhesive materials on optically transparent substrates with microscale lateral dimensions, nanoscale vertical dimensions, molecular vertical precision, and flexibility in material selection has important implications for tissue engineering, drug discovery, and basic research in cell biology. Toward this goal, a systematic study on the electrostatic adsorption properties of fluorescein 5-isothiocyanate-gelatin B (FITC-gelatin) was completed. In addition, the integration of protein nanoassembly with microlithographic feature definition was used to pattern three-dimensional FITC-gelatin nanofilms on planar glass substrates. The experimental results indicate that FITC-gelatin is negatively charged at pH 9 and can be alternately assembled with a positively charged polyion, poly(diallyldimethylammonium chloride) (PDDA), to form multilayer films on solid templates with thickness of 5-10 nm per bilayer. Furthermore, images of protein/polymer nanocomposites indicate that LbL-LO is an efficient way to realize the designed substrates. These findings will benefit future research on cell culture and tissue engineering that require methods of generating protein patterns to fabricate novel in vitro cell culture systems. [ABSTRACT FROM PUBLISHER]

In this paper, we investigated the transmission properties of multilayer films composed of magneto-optical and dielectric materials, in relation to layer stacking structure. The basic structures are made of alternating layers of these materials having a conventional symmetric periodicity with the center of the structure. Films with these basic structures exhibit an enhanced Faraday rotation effect. The rotation increases to an angle close to 45°, which is required for an optical isolator, as the repetition number of alternating layers increases. However, the transmittance decreases in these films as the rotation increases. To clarify the possibility of improving the transmittance, we also investigated films composed of multiple stacks of the basic structures. We found that, by using the multiple stacks, the transmittance can be improved without degrading the rotation characteristics [ABSTRACT FROM PUBLISHER]

Compositionally graded magnetic multilayer (CGM) structures were investigated to improve media signal-to-noise ratio (SNR) as well as thermal stability. The medium structure consists of multiple magnetic layers that play an important role in determining the crystallographic texture as well as magnetic activation volume. Low medium noise is achieved while retaining high resolution, as the number of layers is increased. The CGM media offer a magnetic anisotropy gradient from the top to bottom layers, which enhances head writability at high frequencies without affecting thermal stability Improved magnetic and recording properties such as high Ku V/KT, SNR, and overwrite are obtained with CGM media, suitable for high areal density recording. [ABSTRACT FROM AUTHOR]