Theory of Point Contact Spectroscopy in Correlated Materials

Abstract

We develop a microscopic theory for the point-contact conductance between a metalic electrode and a strongly correlated material using the non-equilibrium Schwinger-Kadanoff-Baym-Keldysh formalism. We explicitly show that in the classical limit, contact size shorter than the scattering length of the system, the microscopic model can be reduced to an effective model with transfer matrix elements that conserve in-plane momentum. We find that the conductance $dI/dV$ is proportional to the {\it effective density of states}, that is, the integrated single-particle spectral function $A(\omega =eV)$ over the whole Brillouin zone. From this conclusion, we are able to establish the conditions under which a non-Fermi liquid metal exhibits a zero-bias peak in the conductance. This finding is discussed in the context of recent point-contact spectroscopy on the iron pnictides and chalcogenides which has exhibited a zero-bias conductance peak.

arXiv comment8 pages, 3 figures, submitted to PNAS, some typos are fixed

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Cited by in corpus (11)

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• Enhanced superconductivity at the interface of W/Sr${}_2$RuO${}_4$ point contact
• Direct observation of ballistic Andreev reflection
• Hybridization gap in the heavy-fermion compound UPd${}_2$Al${}_3$ via quasiparticle scattering spectroscopy
• Automated fabrication technique of gold tips for use in point-contact spectroscopy
• Design and construction of a point-contact spectroscopy rig with lateral scanning capability
• Atomic scale imaging of sign-changing order parameter in superconducting FeSe with Tunneling Andreev Reflection
• Superconductivity-Induced Changes in Density-Density Correlation Function Enabled by Umklapp Processes
• Recent Progress of Point Contact Spectroscopy as a Probe of Correlated Electron States
• Spatial interferences in the electron transport of heavy fermion materials