A Four Unit Cell Periodic Pattern of Quasi-Particle States Surrounding Vortex Cores in Bi ₂ Sr ₂ CaCu ₂ O _8+δ

Abstract

Scanning tunneling microscopy is used to image the additional quasi-particle states generated by quantized vortices in the high critical temperature superconductor Bi2Sr2CaCu2O8+delta. They exhibit a copper-oxygen bond-oriented "checkerboard" pattern, with four unit cell (4a0) periodicity and a approximately 30 angstrom decay length. These electronic modulations may be related to the magnetic field-induced, 8a0 periodic, spin density modulations with decay length of approximately 70 angstroms recently discovered in La1.84Sr0.16CuO4. The proposed explanation is a spin density wave localized surrounding each vortex core. General theoretical principles predict that, in the cuprates, a localized spin modulation of wavelength lambda should be associated with a corresponding electronic modulation of wavelength lambda/2, in good agreement with our observations.

d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

“…An enhancement of incommensurate static order was observed on increasing the applied magnetic field up to 14 T [2]. Because the signal disappeared above T c , the magnetism was attributed to the vortices; indeed, scanning tunneling microscopy (STM) measurements [7] on Bi 2 Sr 2 CaCu 2 O 8+δ (BSSCO) were able to directly image unusual charge order near the vortex cores, which is almost certainly related to the field-induced SDW detected by neutron scattering.…”

Quasiparticle interference and the interplay between superconductivity and density wave order in the cuprates

“…32 In addition to dispersing octet q-vectors from superconducting QPI, static quasi-periodic "checkerboard" modulations have been observed in both the superconducting and pseudogap phases. 13,15,[17][18][19][21][22][23][24]26,27 Although the origin of these modulations remains unknown, there has been much discussion about their relation to a possible DW order in the pseudogap phase; scenarios that have been proposed include orbital current induced d-density waves, 33 one dimensional stripes, 34 nematic order, 35 short range charge order connected to nested parts of the Fermi surface in antinodal regions, 23,[36][37][38] and disorder-induced charge orders. 39 We present a detailed study of what can be learned from the Z-map in superconducting, DW, and coexisting phases.…”

“…1,8,9 STS has revealed that the cuprates have a spatially inhomogeneous electronic structure, including modulations in the LDOS and superconducting gap magnitude. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] In the d-wave superconducting phase, the LDOS modulations can arise from quasiparticle interference (QPI), due to the scattering of wave-like quasiparticles off impurities. 12,15,22,[25][26][27] The wavevectors of the modulations can be determined from the Fourier transform of the LDOS.…”

Pebbles in the nodal pond

“…Although the presence of a very weak remnant of stripe order in the best superconductors is still debated 1,6 , stripes usually appear only when superconductivity is suppressed. Magnetic fields are the natural enemy of superconductivity: patches of stripe-like order around lines of concentrated magnetic flux (vortices) have already been detected in STM images 10,11 . Do stripes destroy the nodal fermions?…”