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[en] In three-component superlattices of [(NdMnO3)n/(SrMnO3)n/(LaMnO3)n]m consisting of nonferroelectric and antiferromagnetic layers, the generation of coherent phonons in the system is investigated by the relaxation process of the superlattice using a pump–probe technique. The coherent phonons are related to MnO6 octahedra in the layers. While the frequency of the phonons is 49 GHz without regard to the period of each layer, the amplitude of the phonons is influenced by the period of the superlattices. The superlattices have the maximum amplitude of the acoustic phonons at a period of (5, 12) together with strong emergent interfacial effects such as ferromagnetism and ferroelectricity, which are not present in bulk materials. This implies a possible correlation of the lattice structure with interface-induced properties.
[en] The phonon thermal conductivity of a multilayer is calculated for transport perpendicular to the layers. There is a crossover between particle transport for thick layers to wave transport for thin layers. The calculations show that the conductivity has a minimum value for a layer thickness somewhat smaller then the mean free path of the phonons. (c) 2000 The American Physical Society
[en] In this chapter the role of neutron diffraction in the study of magnetic superlattices is described. The fundamental principles of neutron diffraction pertinent to such studies are first discussed followed by a number of actual examples that are both physically interesting and illustrative of the power of the method. 54 refs.; 6 figs.; 3 tabs
[en] Partial electron localization in a finite-size superlattice placed in an electric field is considered. The role of electric field in forming of quasilocalized states is investigated. A quantitative criterion for the degree of partial localization is suggested based on analysis of maximal probability density of finding an electron at a given point. It is found that with increase in the electric field the degree of localization does not increase monotonically. Furthermore, the localization is affected stronger by the amplitude of superlattice potential than by the electric field.
[en] Research highlights: → This paper is dedicated to structures based on Cd1-xZnxS. - Abstract: The present work reports on a theoretical investigation of superlattices based on Cd1-xZnxS quantum dots embedded in an insulating material. The system to model is assumed to be a series of flattened cylindrical quantum dots with a finite barrier at the boundary and is studied using a sinusoidal potential. The electronic states of both Γ1 - (ground) and Γ2 - (first excited) minibands have been computed as a function of inter-quantum dot separation and Zn composition. An analysis of the results shows that the widths of Γ1 - and Γ2 - minibands decrease as the superlattice period and Zn content increase separately. Moreover, the sinusoidal shape of the confining potential accounts for the coupling between quantum dots quantitatively less than the Kronig-Penney potential model.
[en] Atomistic simulations show that there are long-ranged ferroelectric interactions between the ferroelectric layers in ferroelectric/paraelectric superlattices mediated by continuous chains of polarization running through the intervening paraelectric layers. The resulting behavior of the superlattice is strongly dependent on the modulation length. At short modulation lengths the superlattice acts as a single-component system; at long modulation lengths the individual ferroelectric layers act almost independently
[en] We propose new confinement structures similar to heterostructures and superlattices. The new heterostructures can be obtained by applying strain to a single material in a periodic or aperiodic way. The conversion of an indirect gap into an optical active direct or quasi-direct gap problem has also been investigated together with the role of zone folding in this phenomenon. (author)