2,253 research outputs found
Type-II Bose-Mott insulators
The Mott insulating state formed from bosons is ubiquitous in solid He-4,
cold atom systems, Josephson junction networks and perhaps underdoped high-Tc
superconductors. We predict that close to the quantum phase transition to the
superconducting state the Mott insulator is not at all as featureless as is
commonly believed. In three dimensions there is a phase transition to a low
temperature state where, under influence of an external current, a
superconducting state consisting of a regular array of 'wires' that each carry
a quantized flux of supercurrent is realized. This prediction of the "type-II
Mott insulator" follows from a field theoretical weak-strong duality, showing
that this 'current lattice' is the dual of the famous Abrikosov lattice of
magnetic fluxes in normal superconductors. We argue that this can be exploited
to investigate experimentally whether preformed Cooper pairs exist in high-Tc
superconductors.Comment: RevTeX, 17 pages, 6 figures, published versio
Topological Order in the Phase Diagram for High-Temperature Superconductors with Point Defects
Applying a Lindemann-like criterion obtained previously by Kierfeld,
Nattermann and Hwa [Phys. Rev. B 55, 626 (1997)], we estimate the magnetic
field and temperature for a high- superconductor, at which a topologically
ordered vortex glass phase becomes unstable with respect to a disorder-induced
formation of dislocations. The employed criterion is shown to be equivalent to
a conventional phenomenological Lindemann criterion including the values for
the numerical factors, i.e., for the Lindemann-number. The positional
correlation length of the topologically ordered vortex glass is calculated.Comment: 8 pages, REVTEX 3.0, uses epsf, 1 eps-figure, major changes:
Lindemann-like criterion is applied to YBCO, the electromagnetic coupling and
the possibility of strong pinning are considered, version accepted for
publication in Physica
The Post-Merger Magnetized Evolution of White Dwarf Binaries: The Double-Degenerate Channel of Sub-Chandrasekhar Type Ia Supernovae and the Formation of Magnetized White Dwarfs
Type Ia supernovae (SNe Ia) play a crucial role as standardizable
cosmological candles, though the nature of their progenitors is a subject of
active investigation. Recent observational and theoretical work has pointed to
merging white dwarf binaries, referred to as the double-degenerate channel, as
the possible progenitor systems for some SNe Ia. Additionally, recent
theoretical work suggests that mergers which fail to detonate may produce
magnetized, rapidly-rotating white dwarfs. In this paper, we present the first
multidimensional simulations of the post-merger evolution of white dwarf
binaries to include the effect of the magnetic field. In these systems, the two
white dwarfs complete a final merger on a dynamical timescale, and are tidally
disrupted, producing a rapidly-rotating white dwarf merger surrounded by a hot
corona and a thick, differentially-rotating disk. The disk is strongly
susceptible to the magnetorotational instability (MRI), and we demonstrate that
this leads to the rapid growth of an initially dynamically weak magnetic field
in the disk, the spin-down of the white dwarf merger, and to the subsequent
central ignition of the white dwarf merger. Additionally, these magnetized
models exhibit new features not present in prior hydrodynamic studies of white
dwarf mergers, including the development of MRI turbulence in the hot disk,
magnetized outflows carrying a significant fraction of the disk mass, and the
magnetization of the white dwarf merger to field strengths
G. We discuss the impact of our findings on the origins, circumstellar media,
and observed properties of SNe Ia and magnetized white dwarfs.Comment: Accepted ApJ version published on 8/20/13, with significant
additional text added discussing the nature of the magnetized outflows, and
possible CSM observational features relevant to NaID detection
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