Tunneling Density of States of HighTcSuperconductors:d-Wave BCS Model versus SU(2) Slave-Boson Model

Abstract

Motivated by recent experimental measurements of the tunneling characteristics of high Tc materials using scanning tunneling spectroscopy, we have calculated the IV and differential conductance curves in the superconducting state at zero temperature. Comparing the two results obtained via BCS-like d-wave pairing and the SU (2) slave boson approach, we find that the slave-boson model can explain the asymmetric background observed in experiments. The slave-boson model also predicts that the height of the conductance peak relative to the background is proportional to the hole doping concentration x, at least for under-doped samples. We also observe the absence of the van Hove singularity, and comment on possible implications.

Bogoliubov angle and visualization of particle-hole mixture in superconductors

“…One possibility is that the apparent shift of the distribution is caused by asymmetric background in the tunneling spectrum 23 that is sampled more at higher voltage as we shall see in the Fig. 5f.…”

Proposed Design of a Josephson Diode

“…A universal asymmetric density between positive and negative bias voltage in STM experiments [14 -16] has been observed, which can been explained by considering an insulating competing order at surface [17][18][19][20]. This is an important support for the possible realization of the proposed junction, although other alternative explanations [21,22] also exist. The key to create the Josephson diode junction is a spatially selective doping control in cuprates.…”

Tunneling matrix elements with antiferromagnetic Gutzwiller wave functions

“…44 An important feature in tunneling spectra for correlated materials is the particle-hole asymmetry. [45][46][47][48][49][50][51][52][53][54] In uncorrelated materials the spectral weight for the excitations is symmetrical in its particle and hole side. This implies that the probability of adding or removing one electron is the same.…”