2,262 research outputs found
The cluster glass state in the two-dimensional extended t-J model
The recent observation of an electronic cluster glass state composed of
random domains with unidirectional modulation of charge density and/or spin
density on Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} reinvigorates the debate of
existence of competing interactions and their importance in high temperature
superconductivity. By using a variational approach, here we show that the
presence of the cluster glass state is actually an inherent nature of the model
based on the antiferromagnetic interaction (J) only, i.e. the well known t-J
model. There is no need yet to introduce a competing interaction to understand
the existence of the cluster glass state. The long-range pairing correlation is
not much influenced by the disorder in the glass state which also has nodes and
linear density of states. In the antinodal region, the spectral weight is
almost completely suppressed. The modulation also produces subgap structures
inside the "coherent" peaks of the local density of states.Comment: 9 pages, 5 figures, submitted to PR
Mechanism of formation of half-doped stripes in underdoped cuprates
Using a variational Monte-Carlo approach with a recently proposed stripe wave
function, we showed that the strong correlation included in a t-J-type model
has essentially all the necessary ingredients to form these stripes with
modulations of charge density, spin magnetization, and pair field. If a
perturbative effect of electron-phonon coupling to renormalize the effective
mass or the hopping rate of holes is considered with the model, we find the
half-doped stripes, which has on the average one half of a hole in one period
of charge modulation, to be most stable, energetic wise in the underdoped
region, . This is in good agreement with the observation
in the neutron scattering experiments. We also find long range Coulomb
interaction to be less effective in the formation of half-doped stripes.Comment: 4 pages, 4 figure
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