Scanning tunneling microscopy (STM) by providing images of the effects of individual zinc-impurities in cuprate superconductors with unprecedented atomic-resolution offers a stringent test to models of correlated fermions for high-temperature superconductors. Using a t-J model supplemented by Variational Monte Carlo many-body techniques, the spatial dependence of the hole density and of the valence bond and superconducting pairing amplitudes around the impurity are computed. A cross-shaped four-fold symmetric structure very similar to the observed STM observation is found, giving strong credit to the model.
Scanning tunneling microscopy (STM) by providing images of the effects of individual zinc impurities in cuprate superconductors with unprecedented atomic resolution offers a stringent test to models of correlated fermions for high-temperature superconductors. Using a $t\text{\ensuremath{-}}J$ model supplemented by variational Monte Carlo many-body techniques, the spatial dependence of the hole density and of the valence bond and superconducting pairing amplitudes around the impurity are computed. Our calculation supplemented by the theory of interlayer tunneling by I. Martin et al. [Phys. Rev. Lett. 88, 097003 (2002)] can explain most features of the STM experiments including the cross-shaped spatial structure and the impurity ``resonant'' peak.
We investigate the impurity resonant state induced by nonmagnetic impurities in
d-wave cuprate superconductors in two different impurity models: (i) in a pure potential scattering model within the
T-matrix approach and (ii) in a Bose--Fermi Kondo model within the large-
N formalism. We modify the superconducting host to resemble the nanoscale electronic inhomogeneities seen in the scanning tunneling microscopy (STM) spectra (i.e., the small-and large-gap domains) and study how this influences the impurity resonance. In the pure potential scattering model, the resonant state is found to be a rather robust feature appearing in all host domains. On the other hand, in the Kondo-like model the impurity resonance can appear in the small-gap regions of the host and be completely suppressed in the large-gap regions; this is in agreement with the STM experimental data for Zn-doped ${\text{Bi}}_{2}{\text{Sr}}_{2}{\text{CaCu}}_{2}{\text{O}}_{8+\ensuremath{\delta}}$. Our results imply that the Kondo spin dynamics of the impurity moment is the origin of the impurity resonant state in
d-wave superconductors, rather than the pure potential scattering.