The method of linear equations was applied to nonzero temperatures. Two models were considered. The first is the disordered model of random ferromagnetic and antiferromagnetic integrals whose transition matrix meets the condition of invariance of the sum of terms in each line. Although the other model (one-dimensional Ising model in an external field) is devoid of disorder it does not require any assumptions on the form of the transition matrix.
The energies and entropies of the one-dimensional ± J Ising models on square lattices have been compared. The method proposed in this paper explains the impossibility of getting exact results in nonzero temperatures and specifies the conditions of error minimisation.
The dynamics being modifications of the Glauber one were proposed. The time course of the single spin and two-spin correlation function was determined. These calculations were performed for ordered systems, although a possibility of their extension over disordered ones was indicated.
The relaxation process, through which the inequilibrium state described by the Ising model reaches the equilibrium state, was proposed. The process is defined by the action of the transition matrix on the vector of state and the demand of its normalisation. It is assumed that in the state of inequilibrium the vector of state has the same functional dependence as the eigenvector of the transition matrix corresponding to the highest eigenvalue. Two cases are considered: when the cell under transformation is composed of one or two sites. The calculations were performed for a uniform initial state. For the two cases of one and two-site cells the modes of reaching the equilibrium state via magnetisation were compared. When the external magnetic field and temperature tend to zero, both magnetisation and the correlation function of the nearest neighbours show the critical slowing down phenomenon.
An approximation scheme related to the averaging procedure over finite fragments of the lattice was proposed. The magnetisation and entropy were calculated numerically. The correctness of this approximation scheme was analysed against the magnetic field and temperature.
A direct comparison between the Hall effects and giant magnetoresistance of ferromagnetic multilayers of similar composition (Ni_{80}Fe_{20}/Au/Co/Au)_N with alternating in-plane and out-of-plane magnetization direction of Co layers is presented. The characteristic features at magnetic field-dependence of giant magnetoresistance were correlated with the creation and annihilation of the stripe domains in Co layer, with perpendicular anisotropy. The nucleation field values were investigated as an Au layer thickness function. Furthermore, the in situ conductance measurement results characterised the island growth mode of the ferromagnetic layers. The percolation thicknesses were also indicated.
Thermodynamics of one-dimensional finite-ranged Ising model with quenched disorder introduced by random admixture of bonds with second neighbours by means of transfer-matrix method was determined. The influence of frustrations and competition on the internal energy, specific heat, correlations functions, and susceptibility was studied.
We investigated a ±J Ising model on an infinite strip of squares of the width of one and two bonds with a random distribution of ferro- and antiferromagnetic exchange interactions. The exact ground-state energy as a function of the concentration of antiferromagnetic bonds was derived and its singular points in the complex-plane were found.
A correlation between the growth process and electrical properties of [Ni_{80}Fe_{20}(2 nm)/Au(2 nm)/Co(0.8 nm)/Au(2 nm)]_{15} multilayers is presented. A set of multilayers of identical composition was deposited in different temperatures. The changes in giant magnetoresistance amplitude were correlated with the changes in Co layers growth process that occur in different temperatures. The in situ conductance measurement leads to the growth mechanism identification in high temperatures as formation of Co islands. Intensified islandisation of Co was eventually confirmed by the temperature changes in shape of the Hall voltage loops, and the evolution of Co layers contribution.
In this contribution the in situ conductance vs. deposition time dependences of Fe/Si multilayers are analysed. The plot of resistance multiplied by the square of the thickness as a function of iron thickness shows that during the iron deposition initially amorphous-like Fe-Si mixture is formed, next the mixture crystallises, and finally bcc-Fe phase appears. The interface mixing is also manifested by the reduction of the total multilayer thickness measured by small angle X-ray diffraction.
In the following we present the role of surface scattering at Au/Co and Au/Ni-Fe interfaces in Ni-Fe/Au/Co/Au multilayers deposited in different temperatures. Specularity parameter, which describes the electron scattering, is calculated from fitting in situ collected conductance data with the Fuchs-Namba-Tesanovic model. Application of the parallel resistors model enabled to depict changes between Au/Co and Au/Ni-Fe interfaces within multilayers for each repetition. The correlation between enhanced grain boundary scattering for higher deposition temperatures and surface roughness of Ni-Fe/Au/Co/Au multilayers is found.
In this paper we study Fe/Si and Fe/Ge multilayers prepared at room temperature by magnetron sputtering. In situ conductance measurements reveal the formation of interfacial Fe-Si and Fe-Ge mixtures. During the Fe deposition a modification of growth mode is noticed. Deposition of Si (or Ge) onto Fe leads to the reduction of the Fe layer thickness due to interdiffusion, and Fe-Si (or Fe-Ge) structures appear. Above about 1.3 nm of deposited Si (1.5 nm of Ge) nominally pure Si (Ge) starts growing. Surface topography of the Fe/Si multilayers is studied by atomic force microscopy.
Sputter deposited (Ni_{80}Fe_{20}/Au/Co/Au)_{10} multilayers, characterized by alternating in-plane and perpendicular anisotropies of the NiFe and Co layers, respectively, and out-of-plane stripe (labyrinth) domain structure in the Co layers, were bombarded by He^+-ions (10 keV) through a mask consisting of polystyrene nanospheres with a diameter of 470 nm. The changes of multilayers magnetic properties after ion bombardment are correlated with the used mask structure.
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