Chemical order and crystallographic texture of FePd:Cu thin alloy films

FePd thin films have been recently considered as promising material for high-density magnetic storage devices. However, it is necessary to find a proper method of fabrication for the (001)-textured and chemically well-ordered alloy. In this paper, we present the detailed investigations of lattice parameters, chemical order degree, grain sizes and crystallographic texture, carried out on FePd alloys with 10 at.% of Cu addition. The initial [Cu(0.2 nm)/Fe(0.9 nm)/Pd(1.1 nm)]x5 multilayers were thermally evaporated in an ultra-high vacuum on MgO(100), Si(100), Si(111) and Si(100) covered by 100 nm thick layer of amorphous SiO2. In order to obtain homogeneous FePd:Cu alloy, the multilayers were annealed in two different ways. First, the samples were rapidly annealed in nitrogen atmosphere at 600oC for 90 seconds. Next, the long annealing in a high vacuum for 1 hour at 700oC was done. This paper focuses on quantitative investigations of the chemical order degree and crystallographic texture of ternary FePd:Cu alloys deposited on four different substrates. In order to obtain both quantities we have taken a novel approach to consider the problem of dopant atoms located in the FePd structure. The studies of the structure were done using X-Ray Diffraction (XRD) performed with synchrotron radiation and pole figures measurements. We have found that the addition of Cu changes the FePd lattice parameters and lattice distortion. We have also shown, that using different substrates it is possible to obtain a FePd:Cu alloy with different chemical order and texture. Moreover, it was observed that texture category is substrate dependent

AES Studies of Saturation in Surfactant Segregation Process in Co/Cu Multilayers

The chemical composition of successive layers in a Co/Cu multilayered system was studied during growth with Auger electron spectroscopy. Experiments were carried out on a sample with 10 repetitions of Co(1 nm)/Cu(2 nm) evaporated at a very low deposition rate in ultrahigh vacuum. A very small amount of Bi or Pb (0.06 nm) was deposited on each Cu film in the system. The experimental data have shown that the concentration of Bi and Pb increases with the number of deposited trilayers up to coverage corresponding to 5 trilayers. At that point the concentration of the surfactant saturated. The changes in the surfactant concentrations are described with a simple model depicting the interaction of the surfactant atoms with the system and how the evolution of the segregation processes. It allows the prediction of the saturation concentration and helps to explain the behaviour of various elements used as a surfactant. The comparison between the theoretical predictions and the experimental results is also discussed

Direct Laser Interference Patterning: Theory and Application

We simulated and experimentally investigated the formation of periodic structures generated by multibeam interference patterning. The simulations at the different setup geometry show that resulting interference pattern is quasi-periodical. The calculated patterns show that the symmetries of the interference maxima depend mostly on the angles of incidence and that a wide variety of patterns can be obtained. Because of the difficulty in aligning four beams sufficiently well to avoid secondary periodicities, for testing we used a three-beam interference configuration. Atomic force microscopy images showed good correspondence between the experimental and simulated interference image, with flat islands which correspond to the destructive interference and narrow channels which correspond to the constructive interference fringes

Direct Laser Interference Patterning: Theory and Application

We simulated and experimentally investigated the formation of periodic structures generated by multibeam interference patterning. The simulations at the different setup geometry show that resulting interference pattern is quasi-periodical. The calculated patterns show that the symmetries of the interference maxima depend mostly on the angles of incidence and that a wide variety of patterns can be obtained. Because of the difficulty in aligning four beams sufficiently well to avoid secondary periodicities, for testing we used a three-beam interference configuration. Atomic force microscopy images showed good correspondence between the experimental and simulated interference image, with flat islands which correspond to the destructive interference and narrow channels which correspond to the constructive interference fringes

The Behaviour of Surfactants during the Growth of Co/Cu Multilayers

The $[Co(1 nm)//Cu(2 nm)]_N$ multilayers with different numbers of bilayer repetitions (N=3 and 10) were thermally evaporated on Si(100) substrates with a small amount of Bi or Pb deposited only on the first and on the second Cu layer. The chemical composition of the surface after each step of the preparation process was studied by Auger electron spectroscopy. The evolution of the Auger peaks showed the segregation of Bi and Pb surfactants. During the evaporation of the subsequent Co and Cu layers, gradual decrease in the surfactant amount on the surface was observed. No appearance of Co peak on the Cu layer, and Cu peak on the Co layer even for a coverage of a few å indicates the layer continuity. The interface roughness of the surfactant-mediated Co/Cu layers analyzed by X-ray reflectometry (when surfactant was deposited twice) was similar to the pure Co/Cu samples. However, more repetitions of surfactant, by reduction of interface roughness, improve the layer quality

Micropatterning of Silicon Surface by Direct Laser Interference Lithography

Direct laser interference lithography is a new and low cost technique which can generate the line- or dot-like periodic patterns over large areas. In the present work, we report on direct fabrication of micrometer structures on Si surface. In the experiments the pulsed high power Nd:YAG laser operating at 1064 nm wavelength was used. Two-beam configuration with an angle of incidence of 40° was employed and different laser fluences up to 2.11 J/$cm^2$ were tested. Areas about 1 cm in diameter have been processed with a single pulse of 10 ns. The laser treated samples were analyzed by atomic force microscopy to investigate the surface topography and to measure the size and depth of the achieved structures. We observed periodic line-like arrays with grating period of the order of 1 μm

Optical Diffraction Strain Sensor Prepared by Interference Lithography

An optical strain sensor was developed for use in stretchable electronics. It consists of a diffraction grating formed directly on the examined surface illuminated by a laser beam which creates interference pattern. This pattern can then be used to determine axial and lateral strains for a uniaxial stress states. Direct laser interference patterning was employed as a fast processing tool for the preparation of micro- and sub-microgratings. Two coherent beams of Nd:YAG laser with 532 nm wavelength and pulse duration of 10 ns were used to selectively remove material from the irradiated sample surface. This technique creates periodic pattern on the metallized surface of polymeric substrates. New sensors formed by direct laser interference patterning method were able to resolve higher order diffraction maxima, which would be of benefit for strain measurement application. Experimental setup for tensile tests was composed of laser probe, the sensor element, and CCD camera. To extract strain values, we analysed acquired interference pattern images in real time software, developed with LabVIEW environment. This kind of contactless strain sensor is suitable for examination of stretchable electronics component for which conventional tensile tests are either not acceptable or can interfere with its normal operation

Micropatterning of Silicon Surface by Direct Laser Interference Lithography

Direct laser interference lithography is a new and low cost technique which can generate the line- or dot-like periodic patterns over large areas. In the present work, we report on direct fabrication of micrometer structures on Si surface. In the experiments the pulsed high power Nd:YAG laser operating at 1064 nm wavelength was used. Two-beam configuration with an angle of incidence of 40° was employed and different laser fluences up to 2.11 J/$cm^2$ were tested. Areas about 1 cm in diameter have been processed with a single pulse of 10 ns. The laser treated samples were analyzed by atomic force microscopy to investigate the surface topography and to measure the size and depth of the achieved structures. We observed periodic line-like arrays with grating period of the order of 1 μm