6,799 research outputs found

### Charge ordering and interlayer phase coherence in quantum Hall superlattices

The possibility of the existence of states with a spontaneous interlayer
phase coherence in multilayer electron systems in a high perpendicular to the
layers magnetic field is investigated. It is shown that phase coherence can be
established in such systems only within individual pairs of adjacent layers,
while such coherence does not exist between layers of different pairs. The
conditions for stability of the state with interlayer phase coherence against
transition to a charge-ordered state are determined. It is shown that in the
system with the number of layers N\leq 10 these conditions are satisfied at any
value of the interlayer distance d. For N>10 there are two intervals of
stability: at sufficiently large and at sufficiently small d. For N\to \infty
the stability interval in the region of small d vanishesComment: 10 page

### Relaxation of superflow in a network: an application to the dislocation model of supersolidity of helium crystals

We have considered the dislocation network model for the supersolid state in
He-4 crystals. In difference with uniform 2D and 3D systems, the temperature of
superfluid transition T_c in the network is much smaller than the degeneracy
temperature T_d. It is shown that a crossover into a quasi superfluid state
occurs in the temperature interval between T_c and T_d. Below the crossover
temperature the time of decay of the flow increases exponentially under
decrease of the temperature. The crossover has a continuous character and the
crossover temperature does not depend on the density of dislocations.Comment: Corrected typo

### Quenched Dislocation Enhanced Supersolid Ordering

I show using Landau theory that quenched dislocations can facilitate the
supersolid (SS) to normal solid (NS) transition, making it possible for the
transition to occur even if it does not in a dislocation-free crystal. I make
detailed predictions for the dependence of the SS to NS transition temperature
T_c(L), superfluid density %\rho_S(T, L), and specific heat C(T,L) on
temperature T and dislocation spacing L, all of which can be tested against
experiments. The results should also be applicable to an enormous variety of
other systems, including, e.g., ferromagnets.Comment: 5 pages, 2 figure

### Bose-Einstein condensation in a decorated lattice: an application to supersolid

The Bose-Einstein condensation of vacancies in a three-dimensional decorated
lattice is considered. The model describes possible scenario of superfluidity
of solid helium, caused by the presence of zero-point vacancies in a
dislocation network. It is shown that the temperature of Bose-Einstein
condensation decreases under increase of the length of the segments of the
network, and the law of decrease depends essentially on the properties of the
vertexes of the network. If the vertexes correspond to barriers with a small
transparency, the critical temperature is inversely as the square of the length
of the segment. On the contrary, if the vertexes correspond to traps for the
vacancies (it is energetically preferable for the vacancies to localize at the
vertexes), an exponential lowering of the temperature of transition takes
place. The highest temperature of Bose-Einstein condensation is reached in the
intermediate case of vertexes with large transparency, but in the absence of
tendency of localization in them. In the latter case the critical temperature
is inversely as the length of the segment.Comment: 7 page

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