A magnetic helix realizes a one-dimensional magnetic crystal with a period given by the pitch length λh. Its spin-wave excitations-the helimagnons-experience Bragg scattering off this periodicity, leading to gaps in the spectrum that inhibit their propagation along the pitch direction. Using high-resolution inelastic neutron scattering, the resulting band structure of helimagnons was resolved b...

long wave side it appears that there may be some additional bands. The magnitude of this spacing indicates that we have to do with one of the transverse or "deformation" oscillations of the molecule, and the complexity of the bands is evidently due to the existence of several vibrational levels having nearly the same energy. In the case of the ideal linear, molecule with Hooke's law binding the...

The properties of any material are fundamentally determined by its electronic band structure. Each band represents a series of allowed states inside a material, relating electron energy and momentum. The occupied bands, that is, the filled electron states below the Fermi level, can be routinely measured. However, it is remarkably difficult to characterize the empty part of the band structure ex...

We present a method for obtaining well-localized Wannier-like functions ~WF’s! for energy bands that are attached to or mixed with other bands. The present scheme removes the limitation of the usual maximally localized WF’s method @N. Marzari and D. Vanderbilt, Phys. Rev. B 56, 12 847 ~1997!# that the bands of interest should form an isolated group, separated by gaps from higher and lower bands...

highly crystalline and pure lithium metasilicate (li2sio3) and lithium disilicate (li2si2o5) nanomaterials were synthesized by hydrothermal method and characterized by pxrd technique. the changes in the morphology and particle size of the synthesized nanomaterials with reaction time were investigated using sem technique. the uv-vis and photoluminescence spectra of the compounds were studied. th...

We report the energy dispersions of the highest occupied molecular orbitals (HOMO)-derived bands of a pentacene (Pn) thin film, whose in-plane structure resembles closely that of the ab plane of a low-density bulk Pn phase. Our present photoemission result indicates that the overlap of the pi-orbitals of adjacent Pn molecules is larger than what was expected from theoretical calculations. Furth...

We analyze the Scarf potential, which exhibits both discrete energy bound states and energy bands, through the quantum Hamilton-Jacobi approach. The singularity structure and the boundary conditions in the above approach, naturally isolate the bound and periodic states, once the problem is mapped to the zero energy sector of another quasi-exactly solvable quantum problem. The energy eigenvalues...