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

TLDR

Electronic modulations around vortices in Bi2212 may relate to field‑induced spin density waves seen in LSCO, and theory predicts a λ/2 electronic modulation for a λ spin modulation, matching the observed checkerboard pattern. The study proposes that a spin density wave localized around each vortex core explains the observed electronic modulations. Scanning tunneling microscopy images the quasi‑particle states induced by quantized vortices in Bi2212. The quasi‑particle states form a copper‑oxygen bond–oriented checkerboard pattern with a four‑unit‑cell periodicity and a ~30 Å decay length.

Abstract

Scanning tunneling microscopy is used to image the additional quasi-particle states generated by quantized vortices in the high critical temperature superconductor Bi 2 Sr 2 CaCu 2 O 8+δ . They exhibit a copper-oxygen bond–oriented “checkerboard” pattern, with four unit cell (4 a 0 ) periodicity and a ∼30 angstrom decay length. These electronic modulations may be related to the magnetic field–induced, 8 a 0 periodic, spin density modulations with decay length of ∼70 angstroms recently discovered in La 1.84 Sr 0.16 CuO 4 . 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 λ should be associated with a corresponding electronic modulation of wavelength λ/2, in good agreement with our observations.