Two pseudogaps with different energy scales at the antinode of the high-temperature Bi$_2$Sr$_2$CuO$_6$ superconductor using angle-resolved photoemission spectroscopy

TL;DR

This study uses high-resolution ARPES to identify two distinct pseudogaps with different energy scales in the antinodal region of Bi$_2$Sr$_2$CuO$_6$, revealing complex pseudogap phenomena in cuprate superconductors.

Contribution

The paper provides direct experimental evidence of two coexisting pseudogaps with different origins and energy scales in a cuprate superconductor, advancing understanding of pseudogap phenomena.

Findings

Identified two pseudogaps with different energy scales in Bi$_2$Sr$_2$CuO$_6$

One pseudogap relates to $d_{x^2-y^2}$-wave pairing, the other has a larger energy scale

Coexistence of two pseudogaps suggests multiple origins of pseudogap phenomena

Abstract

We have performed high-resolution angle-resolved photoemission spectroscopy on single-layered cuprate Bi$_2$Sr$_2$CuO$_6$ to clarify the origin of the pseudogap. By using various photon energies, we have succeeded in directly observing two different pseudogaps with two different energy scales which coexist in the antinodal region: one reflects the $d_{x^2-y^2}$-wave pairing strength while the other has a larger energy scale suggesting an origin distinct from superconductivity. The observed two-pseudogap behavior provides a key to fully understand the pseudogap phenomena in cuprates.