Universality of scanning tunneling microscopy in cuprate superconductors

Abstract

We consider the problem of local tunneling into cuprate superconductors, combining model based calculations for the superconducting order parameter with wavefunction information obtained from first principles electronic structure. For some time it has been proposed that scanning tunneling microscopy (STM) spectra do not reflect the properties of the superconducting layer in the CuO${}_2$ plane directly beneath the STM tip, but rather a weighted sum of spatially proximate states determined by the details of the tunneling process. These "filter" ideas have been countered with the argument that similar conductance patterns have been seen around impurities and charge ordered states in systems with atomically quite different barrier layers. Here we use a recently developed Wannier function based method to calculate topographies, spectra, conductance maps and normalized conductance maps close to impurities. We find that it is the local planar Cu $d_{x^2-y^2}$ Wannier function, qualitatively similar for many systems, that controls the form of the tunneling spectrum and the spatial patterns near perturbations. We explain how, despite the fact that STM observables depend on the materials-specific details of the tunneling process and setup parameters, there is an overall universality in the qualitative features of conductance spectra. In particular, we discuss why STM results on Bi${}_2$Sr${}_2$CaCu${}_2$O${}_8$ and Ca${}_{2-x}$Na${}_x$CuO${}_2$Cl${}_2$ are essentially identical.

References in corpus (8)

• Scanning tunneling spectroscopy of high-temperature superconductors
• An Intrinsic Bond-Centered Electronic Glass with Unidirectional Domains in Underdoped Cuprates
• How Cooper pairs vanish approaching the Mott insulator in Bi2Sr2CaCu2O8+d
• Evolution of the electronic excitation spectrum with strongly diminishing hole-density in superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}
• Interpretation of scanning tunneling quasiparticle interference and impurity states in cuprates
• Impact of Iron-site defects on Superconductivity in LiFeAs
• Van Hove features in BSCCO(2212) and effective parameters for Ni impurities inferred from STM spectra
• Universal scaling behavior of the c-axis resistivity of high-temperature superconductors

Cited by in corpus (3)

• Atomic manipulation of the gap in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+x}$
• Direct comparison of ARPES, STM, and quantum oscillation data for band structure determination in Sr${}_2$RhO${}_4$
• Atomic-Scale Visualization of the Cuprate Pair Density Wave State