Influence Of Exchange Interactions Research Articles

Preparation of Magnetic Composites Based on Bulk Amorphous Iron Alloys

Iron-based amorphous alloys are characterized by so-called soft magnetic properties. Unfortunately, the geometry of iron-based amorphous materials significantly limits the applicability of these materials. One way to expand the use of these materials is to make composites based on them. As part of this work, rapid-cooled alloys were produced using the injection casting method. On their basis, magnetic composites with the addition of a non-magnetic binder were produced. The results of the structure (XRD) and magnetic properties (VSM) tests of the produced materials are presented. The research results have shown that the decisive impact on the magnetic properties of composites is the fact of the separation of magnetic particles with a non-magnetic binder. In this case, the influence of exchange interactions is dominated by dipole interactions.

Influence of exchange interactions between the components of donor-acceptor pairs on the rate constant of intercombitation conversion in acceptor molecules

Results of experimental investigations into the influence of interaction between components of donor-acceptor mixtures on the rate constant of intercombination conversion in acceptor molecules are presented. It is established that the probability of intercombination transition can change several folds as a result of these interactions.

Magnetic Ion Exchange Interactions in NiO–MgO Solid Solutions

In this work, a review of recent experimental data and their interpretation for NicMg1−c O solid solutions is given. In particular, the influence of exchange interactions between Ni2+ ions on the structural, optical, magnetic, and vibrational properties is discussed.

Relativistic many-body investigation of hyperfine interactions in excitedSstates of alkali metals: Francium and potassium

To enhance the current understanding of mechanisms contributing to magnetic hyperfine interactions in excited states of atomic systems, in particular, alkali-metal atom systems, the hyperfine fields in the excited $5{}^{2}{S}_{1/2}--8{}^{2}{S}_{1/2}$ states of potassium and $8{}^{2}{S}_{1/2}--12{}^{2}{S}_{1/2}$ states of francium atoms have been studied using the relativistic linked-cluster many-body perturbation procedure. The net theoretical values of the hyperfine fields for the excited states studied are in excellent agreement with available experimental data for both atoms. There is a significant decrease in importance of the correlation contribution in going from the ground state to the excited states, the correlation contributions as ratios of the direct contribution decreasing rapidly as one moves to the higher excited states. However, the contribution from the exchange core polarization (ECP) effect is nearly a constant fraction of the direct effect for all the excited states considered. Physical explanations are offered for the observed trends in the contributions from the different mechanisms. A comparison is made of the different contributing effects to the hyperfine fields in potassium and francium to those in the related system, rubidium, studied earlier. Extrapolating from our results to the highly excited states of alkali-metal atoms, referred to as the Rydberg states, it is concluded that in addition to the direct contribution from the excited valence electron to the hyperfine fields, a significant contribution is expected from the ECP effect arising from the influence of exchange interactions between electrons in the valence and core states.

The influence of exchange interactions on surface spin waves in a semi-infinite FeBr2 field-induced metamagnet

Properties of surface spin waves are studied in an FeBr2 field-induced metamagnet that consists of ferromagnetically ordered layers, with intralayer nearest-neighbour ferromagnetic exchange coupling, intralayer next-nearest-neighbour antiferromagnetic exchange coupling and interlayer antiferromagnetic exchange coupling as well as strong three-ion anisotropy. A Green function method is applied to calculate surface spin-wave modes for the (001) surface and for the paramagnetic phase at low temperatures. By allowing the surface exchange parameters to deviate from the bulk values, the full richness of the surface spin-wave spectra is found. The problem of the stability of the ground state of the system is also discussed.

Rare-earth magnetism in cuprates with T'-structure

Abstract Cuprates of composition (Gd1−xRx)2CuO4, R = Pr, Nd, Sm, Eu, have been studied by 155Gd Mossbauer spectroscopy and by complementry experimental techniques. The results provide new evidence for the important influence of exchange interactions between Cu and rare-earth 4f-moments on rare-earth magnetism in these compounds.

Influence of exchange interactions on molecular conformation: stability of the gauche conformers on the 2-haloethanols

The influence of exchange interactions on molecular conformation is illustrated, on the basis of a simple model, by considering their role in stabilizing the gauche conformers of the 2-haloethanols. It is shown that, similar to the case of the n-propyl halides analysed earlier, the stability of the gauche form may be ascribed to three-atom indirect exchange interactions associated to the triplet formed by the halogen atom, the carbon atom belonging to both axes of internal rotation and the hydrogen atom of the hydroxyl group. Also quantitatively, the agreement between calculated and experimental results is satisfactory.

Influence of exchange interactions on molecular conformation: stability of the gauche conformer of n-propylhalides

The influence of exchange interactions on molecular conformations is illustrated by considering their rôle in stabilizing the gauche conformation of the n-propyhalides. The conformational energy is calculated as a sum of exchange interactions for clusters of non-bonded atoms. The exchange component is evaluated in first order of perturbation theory, in the approximation of one “effective” electron per non-bonded atom, plus a three-atom, indirect exchange (“superexchange”) contribyution involving the core electrons of a heavy (halogen) atom in the molecule. It is shown that the greater stability of the gauche form may be due to the three-atom indirect exchange interactions associated to the triplet formed by the halogen atom, the carbon atom belonging to both axes of internal rotation and that the halogen which is facing the halogen atom. We find satisfactory agreement between calculated and experimental results.