Showing papers by "Ternopil Ivan Pul'uj National Technical University published in 2001"
TL;DR: In this paper, the ground state of a double orbitally degenerate model at weak intra-atomic interaction is studied using the Green functions method, which includes correlated hopping integrals and inter-atomic exchange interaction.
Abstract: In the present paper the ground state of a double orbitally degenerate model at weak intra-atomic interaction is studied using the Green functions method. Beside the diagonal matrix elements of electron-electron interactions the model includes correlated hopping integrals and inter-atomic exchange interaction. The influence of orbital degeneracy with Hund's rule coupling, correlated hopping and inter-atomic direct exchange on the ferromagnetic ordering is investigated. The expressions for ground state energy and magnetization, the criterion of transition from paramagnetic to ferromagnetic ground state as functions of the model parameters are obtained. The obtained results are compared with some experimental data for magnetic materials.
15 citations
22 Feb 2001
TL;DR: In this paper, the possibility of defect structure and consequently basic parameters (carrier density, their mobility and lifetimes) control in bulk MCT using the nanosecond laser irradiation induced shock waves (LSW) was investigated.
Abstract: The possibility of defect structure and consequently basic parameters (carrier density, their mobility and lifetimes) control in bulk mercury-cadmium telluride (MCT) using the nanosecond laser irradiation induced shock waves (LSW) is investigated. MCT bulk samples (with composition x equals 0.2) both n- and p- type with different initial structural quality were treated. The post-treatment changes have been detected by galvanomagnetic and photoelectric (lifetime) techniques. Two depending of irradiation mode mechanisms of interaction between LSW and bulk Hg1-XCdXTe defect subsystem are given. The potentiality of this technique as a technological tool for controlled modification of MCT parameters is discussed.
2 citations
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TL;DR: In this article, a possibility of metallic ferromagnetic state realization in a generalized Hubbard model with more complete accounting of electron-electron interactions, in particular, the correlated hopping and exchange interaction integrals is investigated.
Abstract: In the paper a possibility of metallic ferromagnetic state realization in a generalized Hubbard model with more complete accounting of electron-electron interactions, in particular, the correlated hopping and exchange interaction integrals is investigated. Recently obtained by means of mean-field approximation single electron energy spectrum is used for the description of finite temperature properties of the system. In the paper the expression for the critical temperature of ferromagnet-paramagnet transition is found, the behaviour of temperature dependencies of magnetization and paramagnetic susceptibility is analyzed. Taking into account the correlated hopping allows to explain some peculiarity of ferromagnetic behaviour of transition metals, their alloys and compounds.