Theory of magnetooptical effects in thin ferromagnetic films

A systematic theory is derived for the anomalous magnetooptical effects in thin ferromagnetic films for the more general case in which conduction electrons are scattered by both phonons and impurities. The Kohn-Luttinger density-matrix method is used to find the tensor for the complex transverse conductivity, which is linear in the spin-orbit interaction and can be used to find the magnetooptical parameter. The temperature dependences of the real and imaginary parts of the conductivity tensor are found for high temperatures.     

Anomalies of magnetooptical diffraction in ferrite-garnet films

Experimental magnetooptical diffraction spectra produced by the band domain sructure in an epitaxial ferrite-garnet film are described. Asymmetry of the optical field in symmetric maxima is observed when a laser beam is normally incident on the sample. Analysis of the experimental data shows that the factors responsible for disrupting the symmetry of the magnetooptical diffraction spectrum include the inclination of the domain walls and inequality of the Fresnel coefficients fors andp polarizations of the incident radiation. Ul'yanovsk State Unviersyt. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 68–71, September, 1997.     

Optical and magnetooptical properties of Co-doped YIG films

Conclusions Analysis of cobalt contributions to the Faraday rotation spectra in the series of (YCa)₃(FeCoGe)₅O₁₂ garnet films enabled us to distinguish between single contributions of Co²⁺ and Co³ ions in tetrahedral sites. It appeared that even the high counterdopes of calcium do not suppress the occurrence of tetrahedral Co²⁺ ions, although their concentration is greatly reduced in comparison with the original samples not containing any Ca. Noteworthy is also a rather high content of tetrahedral Co³⁺ in the samples not containing calcium even in cases when Ge content exceeds that of Co ions.     

Theory of magnetooptical effects in ferromagnetic metals

Magnetooptical effects in ferromagnetic metals have been studied by the Kohn-Luttinger method, by means of electron scattering by impurity centers. There is a discussion of the more general case, in which the external agent has both a frequency and a wave vector. Solution of the corresponding kinetic equation with an account of the diffusion term reveals the symmetric and antisymmetric parts of the complex average velocity, valid for both high and low frequencies.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 7, pp. 47–50, July, 1969.     

Static magnetic characteristics nonuniform over the thickness of CoNi films

A method based on the meridional magnetooptical intensity effect is used to study the hysteresis loops on opposite sides of thin cobalt-nickel films deposited at a varying angle on a polyethyleneterephthalate substrate. A comparison of the magnetic propertes of the films on the different sides and in the bulk show that these properties change continuously over the thickness. The coercivity is always greater on the side of the film where the angle of deposition is higher. The difference in the magnetic characteristics on the opposite sides of the film is greater in thicker films. Zh. Tekh. Fiz. Zh. Tekh. Fiz. 67, 63–66 (March 1997)     

Theory of magnetooptical effects in ferromagnetic nickel

A theory is developed for magnetooptical effects in ferromagnetic nickel with allowance for the topology of the Fermi surface at low temperatures, when the carriers are scattered on ionized impurity centers. The contribution to the frequency conductivity tensor due to the anisotropy of the Fermi surfaces of nickel is found and it is shown that this contribution in the first approximation of perturbation theory reduces to a decrease of the tensor . An estimate is made of the influence of the density of states of nickel on the anomalous frequency-dependent Hall current and a study is also made of the case of low and high frequencies, when, respectively, ^{2 2} « 1 and ^{2 2} » 1.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 29–33, May, 1972.     

Anisotropy of magnetooptical response of nanoperforated permalloy films

The azimuthal anisotropy of the linear and nonlinear magnetooptical Kerr effect has been studied for a structure that is an ordered array with 420-nm-diameter pores in a 30-nm-thick permalloy film on a silicon substrate. The azimuthal anisotropy of the magnetooptical Kerr effect and the coercive force, corresponding to 4 m symmetry of a planar nanopore array, has been established experimentally. The measurements are accompanied with the numerical calculation of the anisotropic magnetization distribution in the structure at different orientations of the applied magnetic field.     

Ellipsometric measurement of magnetooptical nonreciprocal effects

To detect small rotation rates with a ring laser the two counter-propagating beams must be uncoupled. This lock-off can be realized using nonreciprocal optical effects yielding different optical path lengths for the two waves. Usually magnetooptical effects are employed for nonreciprocity. To measure, instead of calculating from optical constants, the magnitude of this nonreciprocal effects an ellipsometric method is proposed. Lock-off elements using Faraday or Kerr effect (polar and transverse, respectively) are treated. First measurements were made on FeNi films.     

Magnetic and magnetooptical properties of nanothick polycrystalline Co-P films

Features of the formation of chemically deposited polycrystalline Co-P films with nanometer thicknesses are established by magnetic measurements and analysis of film surface morphology. It is found that the specific value of the magnetooptical Faraday effect in Co-P films exceeds that in Co films by a factor of more than two. This is attributed to the magnetic polarization of a Pd underlayer. It is shown the Kerr effect in Co films is negligibly influenced by the embedding of phosphorus.     

Magnetic and magnetooptical properties of Gd-Co-Si films of various thickness

The magnetic, optical, and magnetooptical properties of amorphous Gd-Co-Si films of various thickness are investigated. It is shown that the perpendicular component of anisotropy in the films is preserved to very small thicknesses, down to 0.005 m. The character of the thickness dependence of the anisotropy constant is analyzed and compared with the behavior expected according to a simple theoretical model which assumes that the perpendicular anisotropy originates from the microstructure. It is concluded that the probable source of the perpendicular anisotropy in these materials is the anisotropic distribution of atom pairs.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 70–75, January, 1986.     

Effect of annealing on the magnetic and magnetooptical properties of Ni films

The magnetic and magnetooptical properties of 50-to 200-nm-thick Ni films, both as-deposited and annealed at T_ann = 300, 400, or 500°C, were studied. Volume and near-surface hysteresis loops were measured with a vibrating-sample magnetometer (VSM) and with the use of the transverse Kerr effect (TKE). The annealing temperature was found to exert a strong effect on the magnetic characteristics of the samples under study. It was established, in particular, that the coercivity H _C of Ni films increases and the remanent magnetization decreases with increasing annealing temperature. The observed dependences of the magnetic properties of the films on film thickness and annealing temperature are explained as being due to microstructural characteristics of the samples. It was found that, while TKE spectra obtained in the incident-photon energy region from 1.5 to 6 eV have the same shape for all the Ni films studied, the magnitude of the TKE decreases with increasing T_ann. This experimental observation is accounted for by the decreased saturation magnetization of the annealed films.     

Ferromagnetic and spin-wave resonance in Co/Pd/CoNi multilayer films

It has been found that the magnitude and sign of exchange interaction between Co(5 nm) and CoNi(5 nm) ferromagnetic layers through Pd depend on magnetization orientation of ferromagnetic layers. If magnetization is oriented in a layer plane, exchange interaction can be both ferromagnetic and antiferromagnetic. If magnetization orientation is orthogonal to a layer plane, the exchange constant is always positive at d_Pd<d _c and equals zero at d_Pd>d _c (d _c is the characteristic length).     

Field-induced phase transitions in magnetooptical films with a small positive anisotropy constant

We study phase transitions induced by a static magnetic field in magnetically uniaxial films with a small positive anisotropy constant. The phase diagram of these objects is determined in the H _∥-H _⊥ plane, where H _∥ and H _⊥ are, respectively, the components of the magnetizing field along and perpendicular to the surface normal. The stability boundary is located for all of the main types of domain configurations observed: a simple stripe domain structure, a stripe domain structure with periodic bending by surface distortions in the profile of the domain walls, and hexagonal lattices of cylindrical magnetic bubbles. Zh. éksp. Teor. Fiz. 111, 283–297 (January 1997)     

Combined polaron states in magnetooptical effects in a quantum well

Combined polaron states in a rectangular quantum well in a strong magnetic field perpendicular to the well plane are discussed. These states are due to interaction between two discrete electron levels with different Landau quantum numbers (n and n ₁) and different size-quantization quantum numbers (m and m ₁) on the one hand and a confined LO phonon on the other under conditions of low temperature when the energy difference between the electronic levelsis equal or close to the energy of the confined LO phonon. The expression for the resonant magnetic field H _res at which a combined polaron is formed contains the energy difference between size-quantized levels, so it is a function of quantum well parameters. The separation ΔE _res between branches in the energy spectrum of a combined polaron and H _res has been calculated as a function of the quantum well width d. The resonant field H _res can be reduced dramatically in comparison with the case m=m ₁. The case of size-quantization with n=n ₁ has been analyzed. The energy difference ΔE _res is in the range (1–5)· 10⁻³ eV. The damping of combined polaron states due to the effect of anharmonicity on the LO phonon has been studied. Interband absorption and features in the reflection spectrum due to interband transitions have been calculated for an arbitrary ratio between the radiative and “phonon” lifetime of a combined polaron have been investigated. Zh. éksp. Teor. Fiz. 116, 1419–1439 (October 1999)     

Determination of the reduction depth of tungsten oxide thin films under the effect of proton irradiation

This work is devoted to experimental determination of the limiting reduction depth of tungsten oxide to metal by the measurement of volumetric variations in a thin film of WO₃ under the effect of proton irradiation with an energy of 1.5 keV. The method of radiation-induced reduction of tungsten from WO₃ can be used for preparation of conducting structures in a dielectric matrix and obtaining an inorganic mask for carrying out different ion-beam processes. It is shown experimentally that the effect of a proton beam with an energy of 1.5 keV provides complete reduction of a tungsten oxide layer up to 138 nm thick. The experimental ratio of the thickness of the reduced layer to the thickness of the starting oxide film was 0.31. It is shown that the limiting reduction depth of tungsten oxide is determined by the path of protons in tungsten.     

Slow light phenomenon and extraordinary magnetooptical effects in periodic nanostructured media

Physical nature of the magnetooptical effects enhancement in periodic nanostructured media is investigated. The correlation between group velocity and the Faraday rotation peaks is found. The Faraday rotation gets its maximum values at vanishing group velocity. It is shown that in the vicinity of the photonic band gap the Faraday angle is inversely proportional to the group velocity and directly proportional to the magnetooptical parameter Q averaged along the period of the structure. At this the efficiency of light-magnetic-matter interaction increases significantly. Thus, the increase of the magnetooptical effects in magnetic periodic systems is related to the slow wave phenomenon.     

Determination of concentration-dependent diffusion coefficients in amorphous Ni-P films studied by auger electron depth profiling

Studies of the interdiffusion in ion-plated Ni₁₀₀- _x P _x /Ni₁₀₀- _y /P _y thin films are described. The diffusion coefficients are evaluated from depth profiles obtained by using Auger electron spectroscopy (AES). The well-known Boltzmann-Matano method is applied for extraction of the diffusion coefficients from the depth profile data. The results show a strong composition dependence.     

Relation between magnetooptical effects and the topology of the Fermi surface of ferromagnetic metals

The anomalous magnetooptical effects in transition metals are related to the structure of the Fermi surface. The anisotropy parameters for the scattering of carriers by impurity centers is derived. The anisotropy parameter is calculated for the real and imaginary parts of the anomalous complex conductivity of iron for multiply connected, spin-down cylindrical surfaces around point H of the subband, for the single spin-down electron surface around point of the subband, and for the large spin-up hole surface around point H of the subband.Translated from Izvestiya VUZ. Fizika, No. 5, pp. 23–28, May, 1971.The author thanks professor E. I. Kondorskii.