The Ground State of the Pseudogap in Cuprate Superconductors

TL;DR

This study investigates the electronic structure of La2-xBaxCuO4 near x=1/8, revealing a d-wave energy gap persists without superconductivity, indicating a phase incoherent d-wave state with spin/charge order.

Contribution

It provides evidence that the non-superconducting striped state at x=1/8 is a phase incoherent d-wave superconductor with spin/charge order, expanding understanding of pseudogap phenomena.

Findings

Energy gap consistent with d-wave symmetry detected at x=1/8

Superconductivity suppressed despite the presence of a gap

Striped state exhibits a phase incoherent d-wave pairing

Abstract

We present studies of the electronic structure of La2-xBaxCuO4, a system where the superconductivity is strongly suppressed as static spin and charge orders or "stripes" develop near the doping level of x=1/8. Using angle-resolved photoemission and scanning tunneling microscopy, we detect an energy gap at the Fermi surface with magnitude consistent with d-wave symmetry and with linear density of states, vanishing only at four nodal points, even when superconductivity disappears at x=1/8. Thus, the non-superconducting, "striped" state at x=1/8 is consistent with a phase incoherent d-wave superconductor whose Cooper pairs form spin/charge ordered structures instead of becoming superconducting.