921 research outputs found
Nematicity as a route to a magnetic field-induced spin density wave order; application to the high temperature cuprates
The electronic nematic order characterized by broken rotational symmetry has
been suggested to play an important role in the phase diagram of the high
temperature cuprates. We study the interplay between the electronic nematic
order and a spin density wave order in the presence of a magnetic field. We
show that a cooperation of the nematicity and the magnetic field induces a
finite coupling between the spin density wave and spin-triplet staggered flux
orders. As a consequence of such a coupling, the magnon gap decreases as the
magnetic field increases, and it eventually condenses beyond a critical
magnetic field leading to a field-induced spin density wave order. Both
commensurate and incommensurate orders are studied, and the experimental
implications of our findings are discussed.Comment: 5 pages, 3 figure
Continuum coupled cluster expansion
We review the basics of the coupled-cluster expansion formalism for numerical
solutions of the many-body problem, and we outline the principles of an
approach directed towards an adequate inclusion of continuum effects in the
associated single-energy spectrum. We illustrate our findings by considering
the simple case of a single-particle quantum mechanics problem.Comment: 16 pages, 1 figur
Deuteron Dipole Polarizabilities and Sum Rules
The scalar, vector, and tensor components of the (generalized) deuteron
electric polarizability are calculated, as well as their logarithmic
modifications. Several of these quantities arise in the treatment of the
nuclear corrections to the deuterium Lamb shift and the deuterium hyperfine
structure. A variety of second-generation potential models are used and a
(subjective) error is assigned to the calculations. The zero-range
approximation is used to analyze a subset of the results, and a simple
relativistic version of this approximation is developed.Comment: 14 pages, LaTex - submitted to Physical Review
A geometrical approach to the dynamics of spinor condensates I: Hydrodynamics
In this work, we derive the equations of motion governing the hydrodynamics
of spin-F spinor condensates. We pursue a description based on standard
physical variables (total density and superfluid velocity), alongside 2F
`spin-nodes': unit vectors that describe the spin F state, and also exhibit the
point-group symmetry of a spinor condensate's mean-field ground state. The
hydrodynamic equations of motion consist of a mass continuity equation, 2F
Landau-Lifshitz equations for the spin-nodes, and a modified Euler equation. In
particular, we provide a generalization of the Mermin-Ho relation to spin one,
and find an analytic solution for the skyrmion texture in the incompressible
regime of a spin-half condensate. These results exhibit a beautiful geometrical
structure that underlies the dynamics of spinor condensates.Comment: 12 pages. First paper in two-part serie
ParaSAM: a parallelized version of the significance analysis of microarrays algorithm
Motivation: Significance analysis of microarrays (SAM) is a widely used permutation-based approach to identifying differentially expressed genes in microarray datasets. While SAM is freely available as an Excel plug-in and as an R-package, analyses are often limited for large datasets due to very high memory requirements
Modulated Floquet Topological Insulators
Floquet topological insulators are topological phases of matter generated by
the application of time-periodic perturbations on otherwise conventional
insulators. We demonstrate that spatial variations in the time-periodic
potential lead to localized quasi-stationary states in two-dimensional systems.
These states include one-dimensional interface modes at the nodes of the
external potential, and fractionalized excitations at vortices of the external
potential. We also propose a setup by which light can induce currents in these
systems. We explain these results by showing a close analogy to px+ipy
superconductors
- …