1,162 research outputs found
High-Field Low-Frequency Spin Dynamics
The theory of exchange symmetry of spin ordered states is extended to the
case of high magnetic field. Low frequency spin dynamics equation for
quasi-goldstone mode is derived for two cases of collinear and noncollinear
antiferromagnets.Comment: 2 page
Inverse spectral problems for Sturm--Liouville operators with matrix-valued potentials
We give a complete description of the set of spectral data (eigenvalues and
specially introduced norming constants) for Sturm--Liouville operators on the
interval with matrix-valued potentials in the Sobolev space
and suggest an algorithm reconstructing the potential from the spectral data
that is based on Krein's accelerant method.Comment: 39 pages, uses iopart.cls, iopams.sty and setstack.sty by IO
Is the CPT-norm always positive?
We give an explicit example of an exactly solvable PT-symmetric Hamiltonian
with the unbroken PT symmetry which has one eigenfunction with the zero
PT-norm. The set of its eigenfunctions is not complete in corresponding Hilbert
space and it is non-diagonalizable. In the case of a regular Sturm-Liouville
problem any diagonalizable PT-symmetric Hamiltonian with the unbroken PT
symmetry has a complete set of positive CPT-normalazable eigenfunctions. For
non-diagonalizable
Hamiltonians a complete set of CPT-normalazable functions is possible but the
functions belonging to the root subspace corresponding to multiple zeros of the
characteristic determinant are not eigenfunctions of the Hamiltonian anymore
Structural compliance, misfit strain and stripe nanostructures in cuprate superconductors
Structural compliance is the ability of a crystal structure to accommodate
variations in local atomic bond-lengths without incurring large strain
energies. We show that the structural compliance of cuprates is relatively
small, so that short, highly doped, Cu-O-Cu bonds in stripes are subject to a
tensile misfit strain. We develop a model to describe the effect of misfit
strain on charge ordering in the copper oxygen planes of oxide materials and
illustrate some of the low energy stripe nanostructures that can result.Comment: 4 pages 5 figure
- …