Direct phase-sensitive identification of a d-form factor density wave in underdoped cuprates

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• The fundamental broken symmetry in underdoped cuprates remains an open question.
• Accumulating evidence suggests an unconventional density wave state.

Purpose of the Study:

• To directly visualize and characterize the electronic density wave in underdoped cuprates.
• To determine the symmetry and sublattice modulations of the electronic state.

Main Methods:

• Site-specific electronic structure imaging within the CuO2 unit cell.
• Segregation of results into distinct images for Cu and O sites.
• Phase-resolved Fourier analysis of sublattice modulations.

Main Results:

• Direct visualization of modulations in the O(x)(r) and O(y)(r) sublattices.
• Consistent observation of a relative phase of π between O(x)(r) and O(y)(r) modulations.
• Confirmation across two distinct cuprate compounds, ruling out material-specific artifacts.

Conclusions:

• The density wave in underdoped cuprates exhibits a d-symmetry form factor.
• Direct sublattice phase-resolved visualization confirms the nature of the electronic state.
• The findings resolve ambiguities regarding broken symmetry in these materials.