Plasma resonance guiding of surface magnetoplasmons by thin semiconductor films

Theoretical investigation on surface magnetoplasmons maintained by the plasma resonance in a thin (comparing to the wavelength) semiconducting film placed on a perfectly conducting substrate is presented. Dispersion characteristics and nonreciprocal behaviour of surface magnetoplasmons are studied for arbitrary orientation of externally applied magnetostatic field and for various profiles of film inhomogeneity.     

Ferromagnetic resonance in thin cobalt films

The paper gives the results of measuring ferromagnetic resonance on thin cobalt films, vacuum deposited on unheated glass slides. The values of the (g-factor, the width of the curve, the effective stress and uniaxial induced anisotropy were determined as a function of the thickness of the film from measurements of the ferromagnetic absorption in a magnetic field normal and parallel to the surface of the film. Measurements were carried out on a frequency of 9200 MHz and on film thicknesses of 180 to 1800 Å. A qualitative explanation of the observed dependences is given.

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, . , , g-, , , . 9200 MHz 180–1800 Å. .

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The author thanks V. Kamberský and Z. Málek, C. Sc., for providing some of the cobalt films and for help in depositing and measuring the thicknesses, S. Kadeková and M. Polcarová for valuable advice in determining the structure of the films, J. Míová for carefully plotting the results of measurements and Z. Málek and O. tirand for carefully reading the paper and for valuable discussions.     

X-ray detected ferromagnetic resonance in thin films

We discuss the physical content of X-ray Detected Magnetic Resonance (XDMR), i.e. a novel spectroscopy which uses XMCD to probe the resonant precession of the local magnetization in a strong microwave pump field. We focus on the simplest case of a steady-state precession of elemental moments in the non-linear regime of angular foldover. Like XMCD, XDMR is element and edge selective and could become a unique tool to investigate how precessional dynamics can locally affect the spin and orbital magnetization of p- or d-projected DOS. This should be possible only in the limit where there is no overdamping due to ultrafast orbit-lattice relaxation.     

Doppler-shifted cyclotron resonance in thin metal films

The velocities of electrons contained in a thin slab are quantized because the component of momentum transverse to the slab faces is quantized. For a free electron gas the transverse velocity is given by |v_H| = l(/m) (π/d) where l = 1, 2, 3, …. If a magnetic field is applied normal to the slab, the wave number and frequency dependent conductivity consists of a series of resonant terms. The resonances occur at the Doppler-shifted cyclotron resonance frequencies |ω_c| = ω ± p(/m) (π/d)² where l = 1, 2, 3, …. It is shown that these resonances in the conductivity result in an absorption in pure thin films at low temperatures which is periodic in magnetic field. The semi-classical expression for the absorption is in substantial agreement with the corresponding quantum calculation, and has the virtue that it may be readily extended to non-spherical Fermi surfaces.     

Localized ferromagnetic resonance in inhomogeneous thin films

The effect of sample inhomogeneity on the ferromagnetic resonance linewidth is determined by diagonalization of a spin wave Hamiltonian for ferromagnetic thin films with inhomogeneities spanning a wide range of characteristic length scales. A model inhomogeneity is used that consists of size D grains and an anisotropy field H(p) that varies randomly from grain to grain in a film with thickness d and magnetization M(s). The resulting linewidth agrees well with the two-magnon model for small inhomogeneity, H(p)DpiM(s)d, the precession becomes localized and the spectrum approaches that of local precession on independent grains.     

Water adlayers on aluminum oxide thin films

The effect of saturated water vapor on the performance of quartz cavities covered by magnetronsputtered oxide films is considered. A technique for precisely estimating the influence of small vapor concentrations on the frequency of the quartz cavities is described. Adsorption on the Al₂O₃ surface is characterized with a new model that allows one to list water layers on the surface and correlate the number of adlayers with experimental conditions. The estimated adsorption parameters agree well with available experimental data and results obtained by other authors.     

Pyroelectric and photoelectric responses of capacitors based on thin PZT films

The influence of 0.63-μm laser radiation and an external electric field on the photo-and pyroelectric response of thin ferroelectric Pb(Zr_0.54Ti_0.46)O₃ (PZT) films is studied at various temperatures. The films are grown by RF magnetron sputtering of a PZT ceramic target on platinum-coated substrates. It is found that the photosensitivity of PZT films increases after switching of the applied static electric field, as well as after an increase in temperature.     

Plasma resonance absorption in interfacial photoemission from very thin silver films on Cu(111)

Very thin silver films deposited on a Cu(111) substrate were studied with the photoemission-into-electrolyte technique. The optical resonance absorption at the silver bulk plasma frequency was observed for films thicker than two monolayers. The correlation between optical absorption and photoemission intensities depends in a complicated fashion on the photon energy as well as the film thickness.     

Els investigations of the beginning oxidation on aluminum thin films

ELS and simultaneous quartz microbalance investigations have been carried out on clean aluminum and its surface oxide layer. The loss spectrum of clean Al is interpreted by the collective features of the conduction electrons: volume and surface plasmons, the latter being extremely sensitive to a small oxygen uptake. In the very beginning the oxidation is characterized by a loss peak at 7.3 eV which is attributed to a single electron transition from the O(2p) level to an unfilled state near the Fermi level of the metal. The decreasing intensity of the 7.3 eV loss and the increasing of a second loss at 19.2 eV with further oxygen uptake are tentatively explained by the formation of Al₂O₃ and interband transitions of amorphous Al oxide. The formation of A1₂O₃ is supported by the gravimetric measurements of oxygen mass gain.     

Magnetic resonance line profile in thin superconducting films

Solutions of the modified London equations are derived for a vortex lattice in a thin film from high-temperature superconductors. The nuclear magnetic resonance line profile in the thin film from high-temperature superconductors of different thicknesses d is calculated with allowance for variable inhomogeneity of the local magnetic field of the vortex lattice. It is demonstrated that the nuclear magnetic resonance line profile changes significantly with d, which can give additional information on the superconductor parameters (including the symmetry type of the vortex lattice and the anisotropy parameter Γ). __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 16–19, November, 2005.     

Elastically driven ferromagnetic resonance in nickel thin films

Surface acoustic waves (SAWs) in the GHz frequency range are exploited for the all-elastic excitation and detection of ferromagnetic resonance (FMR) in a ferromagnetic-ferroelectric (Ni/LiNbO(3)) hybrid device. We measure the SAW magnetotransmission at room temperature as a function of frequency, external magnetic field magnitude, and orientation. Our data are well described by a modified Landau-Lifshitz-Gilbert approach, in which a virtual, strain-induced tickle field drives the magnetization precession. This causes a distinct magnetic field orientation dependence of elastically driven FMR that we observe in both model and experiment.     

Room temperature adsorption of water by aluminum thin films

Thin films of aluminum were prepared under ultra-high vacuum conditions in order to investigate the low temperature, low pressure adsorption of water vapor by the aluminum. The kinetics of the water vapor-aluminium reaction have been found to be essentially different than the oxygen-aluminum reaction previously reported. In contrast to the “dry” oxygen uptake kinetics, a plot of the sticking coefficient of H₂O versus the total weight gain of the film indicates that the sticking coefficient of H₂O passes through a maximum. As a result of the present mass adsorption measurements of water by fresh aluminum surfaces and Huber and Kirk's previous contact potential studies of an oxidized aluminum surface upon exposure to water vapor, a model is suggested, based on the simultaneous lateral growth of oxide nuclei and first order adsorption of water dipoles on the growing oxide nuclei surfaces. The model quantitatively describes the kinetics of the mass adsorption of water and also predicts the contact potential behavior of a fresh aluminum surface upon exposure to water vapor. A sticking coefficient of approximately 0.05 is indicated for H₂O on bare aluminum while 0.11 corresponds to the sticking coefficient of water dipoles on the oxide nuclei surfaces.     

Crystallization kinetics of amorphous aluminum–tungsten thin films

82 W₁₈ to Al₆₂W₃₈ compounds ranged from 800 K to 920 K. The activation energy for the crystallization and the Avrami exponent were determined. The results indicated that the crystallization mechanism in films with higher tungsten content was a diffusion-controlled process, whereas in films with the composition similar to the stoichiometric compound (Al₄W), the interface-controlled crystallization probably occurred. Received: 30 March 1998/Accepted: 9 September 1998     

Effect of aluminum on the corrosion behavior of NiTiAl thin films

An electrochemical study for the evaluation of corrosion behavior using potentiodynamic and Tafel techniques was conducted in 0.9% NaCl solution on Ni-Ti and Ni-Ti-Al shape memory thin films. Atomic force microscopy (AFM) and electron probe microanalyzer (EPMA) were applied to observe morphology of the surface film and elemental distribution, respectively, prior to and after immersion in 0.9% NaCl solution. The concentration of dissolved Ni from Ni-Ti-Al thin films in the electrolyte, measured with inductively coupled plasma atomic emission spectrometer (ICP-AES), was significantly lower after immersion for 7 days, as compared to Ni-Ti thin film. This demonstrated that a better corrosion resistance and lower corrosion current density were revealed for Ni-Ti-Al thin films than that for Ni-Ti thin film. The improved corrosion performance of Ni-Ti-Al thin films would be potentially beneficial for related biological applications. This was attributed to the introduction of aluminum after exposure to an aqueous environment.