Local quasiparticle density of states and Fourier transformed local density of states in YBa2Cu3O7-δ (Y-123)

LDOS modulations of Y-123 at H = 5T and 6 K over a (22 x 29) nm2 area FT studies of the conductance maps of Y-123: |F(k,ω)| at H = 5T and ω = -12 meV

Left image

The LDOS modulations of Y-123 at H = 5T and 6 K over a (22 x 29) nm2 area, showing patterns associated with density-wave modulations and vortices (circled objects) for ω = (a) -9 meV ~ -Δ’, (b) -23 meV ~ -ΔSC, (c) -33 meV ~ -VCO and (d) -53 meV. We note that the vortex contrasts are the most apparent at |ω| <~ ΔSC and become nearly invisible for |ω| >>VCO. The vanishing contrast at high energies may be due to the onset of Cu-O optical phonons (~ 50 meV for the cuprates) so that both the collective modes and quasiparticles become scattered inelastically.

Right image

FT studies of the conductance maps of Y-123: |F(k,ω)| at H = 5T and ω = -12 meV. We identify three sets of ω- independent wave-vectors in addition to the reciprocal lattice constants and the (π,π) resonance: QPDW and QCDW along (π,0)/(0,π) and QSDW along (π,π), which are circled for clarity. For more information on the measurements in the hole-type cuprate Y-123, please see arxiv:0906.1776 and arxiv:0808.3016 [Europhys. Lett. 87, 37005 (2009)]. For more information on the vortex-state measurements in the infinite-layer electron-type cuprate La0.1Sr0.9CuO2 (La-112), please seearxiv:0809.0541 [Europhys. Lett. 85, 17004 (2009)]. For a recent review on unconventional low-energy excitations in cuprate superconductors, please see Int. J. Mod. Phys. B 23, 4543 – 4577 (2009).