Time-reversal symmetry breaking versus superstructure

TL;DR

This paper argues that previously observed signals suggesting time-reversal symmetry breaking in cuprates are actually caused by superstructure effects, challenging interpretations of pseudogap phenomena.

Contribution

It clarifies that the dichroism observed in prior experiments is due to superstructure replicas, not spontaneous time-reversal symmetry breaking.

Findings

Dichroism is caused by superstructure effects

No evidence for spontaneous time-reversal symmetry breaking

Reinterpretation of previous experimental results

Abstract

One of the mysteries of modern condenced-matter physics is the nature of the pseudogap state of the superconducting cuprates. Kaminski et al.1 claimed to have observed signatures of time-reversal symmetry breaking in the pseudogap regime in underdoped Bi2Sr2CaCu2O8+d (Bi2212). Here we argue that the observed dichroism is due to the 5x1 superstructure replica of the electronic bands and therefore cannot be considered as evidence for the spontaneous time-reversal symmetry breaking in cuprates.