Pair Density Wave in the Pseudogap State of High Temperature Superconductors

TL;DR

This paper proposes that the low-energy electronic modulations observed in the pseudogap state of high-temperature superconductors are due to a pair density wave of d-wave Cooper pairs lacking global phase coherence, as evidenced by symmetry analysis and model calculations.

Contribution

It introduces the concept of a pair density wave as an explanation for STM observations in the pseudogap state, distinguishing it from other electronic orders.

Findings

STM measurements can differentiate pair density waves from charge density waves.

Symmetry considerations support the pair density wave interpretation.

Model calculations align with experimental observations.

Abstract

Recent scanning tunneling microscopy (STM) experiments of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ have shown evidence of real-space organization of electronic states at low energies in the pseudogap state. We argue based on symmetry considerations as well as model calculations that the experimentally observed modulations are due to a density wave of d-wave Cooper-pairs without global phase coherence. We show that STM measurements can distinguish a pair-density-wave from more typical electronic modulations such as those due to charge density wave ordering or scattering from an onsite periodic potential.