Electronic Structure and X-Ray Photoemission Spectra of MPtSn (M = Ti, Zr, Hf)

The electronic structures of the half-Heusler isostructural compounds TiPtSn, ZrPtSn and HfPtSn were calculated and measured applying the X-ray photoemission spectroscopy. The (Ti, Zr, Hf)PtSn compounds have gaps between the occupied valence band and the empty conduction band, calculated as about 0.75, 1.12, and 1.09 eV, respectively. The calculations were done by the full-potential local orbitals method in the framework of the local spin-density approximation and partly also by the full-potential linear mu±n-tin orbitals method by the LmtART code. Experimental X-ray photoemission spectra were measured using photons of en- ergy of 1486.6 eV. The experimental and calculated spectra match quite well except a small shift in the energy scale

Proceedings of the XII National School "Correlated Electron Systems

In the lecture the theory of spin polarons is reviewed on the basis of its analogy with the theory of lattice polarons. The energy dispersion curve for a single polaron in a two-dimensional antiferromagnetic square lattice is calculated in the self-consistent Born approximation. Also in self-consistent Born approximation the energy of a pair of interacting spin polarons is calculated. The results of calculations for realistic values of parameters of the model lead to the conclusion that pairing of spin polarons is not a likely mechanism of superconductivity in cuprates

Erratum : Damping of the spin wave resonance by dislocations.

No abstract availabl

Damping of the spin wave resonance by dislocations

The relaxation time of long-wavelength magnons is calculated for the mechanism involving two-magnon scattering by dislocations. The results could be used to study the broadening of the spin wave resonance spectrum by dislocations in thin ferromagnetic films.On a calculé le temps de relaxation des magnons aux grandes longueurs d'ondes en tenant compte du mécanisme de diffusion de deux magnons par les dislocations. On applique les résultats obtenus à l'étude de l'élargissement des raies du spectre de résonance des ondes de spin par les dislocations dans les couches minces ferromagnétiques

Spin Polarons in Antiferromagnetic Planes

In the lecture the theory of spin polarons is reviewed on the basis of its analogy with the theory of lattice polarons. The energy dispersion curve for a single polaron in a two-dimensional antiferromagnetic square lattice is calculated in the self-consistent Born approximation. Also in self-consistent Born approximation the energy of a pair of interacting spin polarons is calculated. The results of calculations for realistic values of parameters of the model lead to the conclusion that pairing of spin polarons is not a likely mechanism of superconductivity in cuprates

Spin Polarons in Antiferromagnetic Planes

In the lecture the theory of spin polarons is reviewed on the basis of its analogy with the theory of lattice polarons. The energy dispersion curve for a single polaron in a two-dimensional antiferromagnetic square lattice is calculated in the self-consistent Born approximation. Also in self-consistent Born approximation the energy of a pair of interacting spin polarons is calculated. The results of calculations for realistic values of parameters of the model lead to the conclusion that pairing of spin polarons is not a likely mechanism of superconductivity in cuprates

RELAXATION OF MAGNONS IN THE ITINERANT ELECTRON FERROMAGNETICS

Considérant un modèle de bande simple étroite et tenant compte des interactions magnétiques dipolaires des électrons collectifs, nous avons introduit un Hamiltonien effectif s'exprimant par des opérateurs de création et d'annihilation d'ondes de spin. L'Hamiltonien effectif est employé à étudier le temps de relaxation des ondes de spin. Comme exemple, nous avons calculé le temps de relaxation dû au processus de confluence de trois ondes de spin.The model of a single narrow band is considered and magnetic dipolar interactions of itinerant electrons are taken into account. An effective Hamiltonian is constructed in terms of magnon creation and annihilation operators. The effective Hamiltonian is used to the study of magnon relaxation. As an example, the relaxation time due to 3-magnon confluence processes is calculated

Spin Polarons in Two-Dimensional Systems

The problem of motion of holes on a square lattice of antiferromagnetically ordered spins is considered. An overview of the theory of hole dynamics in the antiferromagnetic background is presented. Motion of a single hole is rather well understood both by numerical and analytical methods. For small but finite concentration of holes a treatment analogous to the standard polaron theory is discussed starting with an exact mapping of the t-J Hamiltonian into holon and pseudospin variables