The magnetic properties of RMn2O5 multiferrroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram both in zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferrolectricity is discussed based on calcula...

Terahertz time-domain spectroscopy was performed to directly probe the low-energy (1-5 meV) electrodynamics of triangular lattice antiferromagnets CuFe(1-x)Ga(x)O2 (x=0.00, 0.01, and 0.035). We discovered an electromagnon (electric-field-active magnon) excitation at 2.3 meV in the paraelectric ↑↑↓↓ collinear magnetic phase, while this electromagnon vanishes in the ferroelectric helimagnetic pha...

Recent research has produced results on subdivision in arbitrary manifolds. These results can be applied to the manifold of lines and thus we can create subdivision schemes especially for ruled surfaces. We present different methods for refining discrete models of ruled surfaces: An algorithm combining subdivision and projection to the manifold of lines in Euclidean three-space. A further algor...

The aim of the paper is on spacelike circular surfaces and singularities in Minkowski 3-space E13. A surface with a stationary radius can be swept out by movable Lorentzian circle following non-null curve, which acts as spine curve. In study, we have represented furnished its geometric properties such striction curves contrasting those ruled surfaces. Subsequently, new type was distinguished na...