1,416 research outputs found
Stripe fractionalization I: the generation of Ising local symmetry
This is part one in a series of two papers dedicated to the notion that the
destruction of the topological order associated with stripe phases is about the
simplest theory controlled by local symmetry: Ising gauge theory. This first
part is intended to be a tutorial- we will exploit the simple physics of the
stripes to vividly display the mathematical beauty of the gauge theory.
Stripes, as they occur in the cuprates, are clearly `topological' in the sense
that the lines of charges are at the same time domain walls in the
antiferromagnet. Imagine that the stripes quantum melt so that all what seems
to be around is a singlet superconductor. What if this domain wall-ness is
still around in a delocalized form? This turns out to be exactly the kind of
`matter' which is described by the Ising gauge theory. The highlight of the
theory is the confinement phenomenon, meaning that when the domain wall-ness
gives up it will do so in a meat-and-potato phase transition. We suggest that
this transition might be the one responsible for the quantum criticality in the
cuprates. In part two, we will become more practical, arguing that another
phase is possible according to the theory. It might be that this quantum
spin-nematic has already been observed in strongly underdoped LSCO
Thermodynamics and quantum criticality in cuprate superconductors
We will present elementary scaling arguments focussed on the thermodynamics
in the proximity of the quantum critical point in the cuprate superconductors.
Extending the analysis centered on the Gr\"uneisen parameter by Rosch, Si and
coworkers to the cuprates, we demonstrate that a combination of specific heat-
and chemical potential measurements can reveal the nature of the zero
temperature singularity. From the known specific heat data it follows that the
effective number of time dimensions has to equal the number of space
dimensions, while we find a total of six scaling laws governing the temperature
and density dependence of the chemical potential, revealing directly the
coupling constant scaling dimension.Comment: 4 pages no figure
Mottness collapse and statistical quantum criticality
We forward here the case that the anomalous electron states found in cuprate
superconductors and related systems are rooted in a deeply non-classical
fermion sign structure. The collapse of Mottness as advocated by Phillips and
supported by recent DCA results on the Hubbard model is setting the necessary
microscopic conditions. The crucial insight is due to Weng who demonstrated
that in the presence of Mottness the fundamental workings of quantum statistics
changes and we will elaborate on the effects of this Weng statistics with an
emphasis on characterizing these further using numerical methods. The pseudogap
physics of the underdoped regime appears as a consequence of the altered
statistics and the profound question is how to connect this by a continuous
quantum phase transition to the overdoped regime ruled by normal Fermi-Dirac
statistics. Proof of principle follows from
Ceperley's constrained path integral formalism where states can be explicitly
constructed showing a merger of
Fermi-Dirac sign structure and scale invariance of the quantum dynamics.Comment: 27 pages, 4 figures, submitted to theme issue of Phil. Trans. R. Soc.
Dynamical stripe correlations and the spin fluctuations in cuprate superconductors
It is conjectured that the anomalous spin dynamics observed in the normal
state of cuprate superconductors might find its origin in a nearly ordered spin
system which is kept in motion by thermally meandering charged domain walls.
`Temperature sets the scale' finds a natural explanation, while a crossover to
a low temperature quantum domain wall fluid is implied.Comment: 3 pages Revtex. To appear in Physica
The specific heat jump at the superconducting transition and the quantum critical nature of the normal state of Pnictide superconductors
Recently it was discovered that the jump in the specific heat at the
superconducting transition in pnictide superconductors is proportional to the
superconducting transition temperature to the third power, with the
superconducting transition temperature varying from 2 to 25 Kelvin including
underdoped and overdoped cases. Relying on standard scaling notions for the
thermodynamics of strongly interacting quantum critical states, it is pointed
out that this behavior is consistent with a normal state that is a quantum
critical metal undergoing a pairing instability.Comment: 4 pages 1 figur
Competition between Hidden Spin and Charge Orderings in Stripe Phase
The correlation between charge and spin orderings in hole-doped
antiferromagnets is studied within an effective model of quantum strings
fluctuating in an antiferromagnetic background. In particular, we perform the
direct estimation of the charge and spin long-range-order parameters by means
of the quantum Monte Carlo simulation. A hidden spin long-range order is found
to be governed by a competition between the two trends caused by increasing
hole mobility: the enhancement of the two-dimensional spin-spin correlation
mediated by hole motions and the reformation of a strong stripe order.Comment: 4 pages, 8 figures. Accepted for publication as a Rapid Communication
in Physical Review
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