16,179 research outputs found
Superfluid Suppression in d-Wave Superconductors due to Disordered Magnetism
The influence of static magnetic correlations on the temperature-dependent
superfluid density \rho_s(T) is calculated for d-wave superconductors. In
self-consistent calculations, itinerant holes form incommensurate spin density
waves (SDW) which coexist with superconductivity. In the clean limit, the
density of states is gapped, and \rho_s(T << T_c) is exponentially activated.
In inhomogeneously-doped cases, the SDW are disordered and both the density of
states and \rho_s(T) obtain forms indistinguishable from those in dirty but
pure d-wave superconductors, in accordance with experiments. We conclude that
the observed collapse of \rho_s at x\approx 0.35 in underdoped YBCO may
plausibly be attributed to the coexistence of SDW and superconductivity.Comment: 6 pages, 5 figures. Expanded discussio
Role of CuO chains in vortex core structure in YBa2Cu3O{7-delta}
The Bogoliubov-deGennes equations are solved for a proximity model for
YBa_2Cu_3O_{7-\delta} in a magnetic field. The model explicitly includes the
effects of the one-dimensional CuO chains, whose influence on the vortex core
structure is studied. The rapid vortex core contraction as a function of field
which is seen experimentally at low magnetic fields is naturally explained by
the presence of the chains.Comment: 9 pages, 5 figure
Emergence of charge order in a staggered loop-current phase of cuprate high-temperature superconductors
We study the emergence of charge ordered phases within a pi-loop current
(piLC) model for the pseudogap based on a three-band model for underdoped
cuprate superconductors. Loop currents and charge ordering are driven by
distinct components of the short-range Coulomb interactions: loop currents
result from the repulsion between nearest-neighbor copper and oxygen orbitals,
while charge order results from repulsion between neighboring oxygen orbitals.
We find that the leading piLC phase has an antiferromagnetic pattern similar to
previously discovered staggered flux phases, and that it emerges abruptly at
hole dopings p below the van Hove filling. Subsequent charge ordering
tendencies in the piLC phase reveal that diagonal d-charge density waves (dCDW)
are suppressed by the loop currents while axial order competes more weakly. In
some cases we find a wide temperature range below the loop-current transition,
over which the susceptibility towards an axial dCDW is large. In these cases,
short-range axial charge order may be induced by doping-related disorder. A
unique feature of the coexisting dCDW and piLC phases is the emergence of an
incommensurate modulation of the loop currents. If the dCDW is biaxial
(checkerboard) then the resulting incommensurate current pattern breaks all
mirror and time-reversal symmetries, thereby allowing for a polar Kerr effect
Signatures of orbital loop currents in the spatially resolved local density of states
Polarized neutron scattering measurements have suggested that intra-unit cell
antiferromagnetism may be associated with the pseudogap phase. Assuming that
loop current order is responsible for the observed magnetism, we calculate some
signatures of such circulating currents in the local density of states around a
single non-magnetic impurity in a coexistence phase with superconductivity. We
find a distinct C4 symmetry breaking near the disorder which is also detectable
in the resulting quasi-particle interference patterns.Comment: 5 pages, 3 figure
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