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The magnetic reconstruction of doped LaMnO3 on the ferroelectric substrate intrinsically involves sizeable carrier inhomogeneity on the scale of one-unit cell due to the charge screening effect at the interface. The small variation in Mn-d valence caused by the inhomogeneity may be responsible for the conflicting magnetic patterns predicted for thick magnetic films. To avoid the complexity resulting from the carrier inhomogeneity, we consider in this paper the magnetic reconstruction of a rigorously carrier homogeneous monocell SrMnO3 film on a BaTiO3 substrate. Stoichiometric SrMnO3 is used to further prevent the film from structural defects and associated Anderson's localization. Our study showed that magnetic reconstruction takes place between nearest-neighbor antiferromagnetic to ferromagnetic structures during polarization reversal of the substrate even if the ground state of bulk SrMnO3 is far away from the magnetic phase boundary. Furthermore, the estimated effective magnetoelectric coupling coefficient is 6.1 × 10−2 Oe cm V−1. It is more than doubled than those values obtained for thick magnetic films. Our detailed analysis suggested that the magnetic reconstruction is dictated by the modulated double-exchange ferromagnetic coupling mediated by Mn-d(eg)-orbitals against the superexchange antiferromagnetic coupling mediated by d(t2g)-orbitals. The nearest-chain antiferromagnetic structure also appears during the polarization reversal process. [ABSTRACT FROM AUTHOR]

We discuss the limitation of metallic wire structures as absorbers of high intensity electromagnetic radiation due to the large local electrical fields developed at junctions and free ends of the wires. We find that at resonance the breakdown external electric field applied to the body of the wire structure is smaller by several orders of magnitude than the dielectric breakdown field induced at the ends of the wire. We consider the double split ring structure and find that it can offer an enhancement of the Ohmic power absorbed by an order of magnitude over those of single component systems. For multiple connected wire structures we find classes of resonant modes with zero local fields at the junctions but the fields at the free wire ends remain finite. [ABSTRACT FROM AUTHOR]

We generalize Kirchoff’s law for multiply connected wire networks to finite frequencies. We focus on the boundary conditions not present in the conventional Kirchoff’s law at joints when more than three wires come together, which is absent in our previous “circuit theory” for the finite frequency properties of metallic wire networks for singly connected structures. These boundary conditions at the joints involve introducing localized boundary electric fields, in addition to the electric fields of inductive and capacitive origins. The boundary fields act as natural “Lagrange multipliers” for imposing the boundary conditions on the circuit currents. In this way the number of equations is the same as the number of unknowns. The eigenmodes determine not only the circuit current and charge profiles, but also the boundary electric fields which supplement such profiles. The application to T- and H-shape metallic wire networks suggests that the basic types of resonances are mainly controlled by the symmetry and the wire dimensions of the networks. The low frequency modes form along the longest connected paths of the wire network while the high frequency modes can be generated via succeedingly adding more nodes along these various wire paths. The characteristic behavior of the electric and magnetic responses can be inferred from the circuit current profile of a given mode, which offers a simple physical picture on circuit design with particular electromagnetic parameters. [ABSTRACT FROM AUTHOR]

Scrutinyite SnO2 was synthesized by annealing SnO nanoparticles fabricated from micron-size SnO via ball milling. The isotropic as well as anisotropic chemical shifts of 119Sn obtained by solid-state nuclear magnetic resonance method, were verified computationally using a pseudopotential method in density-functional theory. The results fit with 6-fold coordinated Sn. A linear relationship holds empirically between isotropic shift and coordination number divided by Sn-O average bond length in all polymorphs of tin oxides. When the annealing proceeded in an oxygen-free atmosphere, metallic tin, the rutile phase of SnO2 and oxygen vacancies associated with permanent electric dipoles were also detected by thermal analysis and dielectric spectroscopy. [ABSTRACT FROM AUTHOR]

Step-edge guided Gd one-dimensional atomic strings on Ag(111) surface are studied by scanning tunneling microscopy and spectroscopy at low temperature. Spectroscopy measurements show a characteristic peak, 65 meV above Fermi level in sharp contrast with tight-binding calculations of a string on a flat terrace. Good agreement can be obtained when the step edges are included in the calculations, revealing their roles on the electronic spectra of the self-assembled strings guided by step edges. The results are further confirmed by the spectroscopy study of Fe strings on a flat terrace and near step edges constructed by atomic manipulation. [ABSTRACT FROM AUTHOR]