The Origin of the Pseudogap from Tunneling Spectroscopy Measurements on Bi-2212 Single Crystals

TL;DR

This study uses tunneling spectroscopy on Bi-2212 single crystals to identify the pseudogap's origin, concluding it is due to antiferromagnetic correlations rather than other models.

Contribution

It provides experimental evidence favoring the antiferromagnetic correlation model as the origin of the pseudogap in Bi-2212.

Findings

Pseudogap temperature T* is 280-290 K for over-doped samples and above 290 K for under-doped.

Data fits only the antiferromagnetic correlation gap model.

Supports AF correlations as the pseudogap origin.

Abstract

We present electron-tunneling spectroscopy of oxygen over- and under-doped Bi-2212 single crystals in a temperature range between 14 K and 290 K using a break-junction technique. In over- and under-doped samples we observe a pseudogap with T* = 280 - 290 K and T* > 290 K, respectively. In order to explain the data we consider possible models for the pseudogap, namely, (i) a precursor pairing; (ii) a charge-density-wave gap; (iii) a spin-gap due to antiferromagnetic (AF) correlations. Analyzing all data we show unambiguously that the only model which fits the data is a gap due to AF correlations.