Electron Glass Phase with Resilient Zhang-Rice Singlets in LiCu_{3}O_{3}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• LiCu3O3 is an antiferromagnetic mixed-valence cuprate with a complex layered structure.
• It features edge-sharing Cu(II)O3 trilayers and Cu(I) planes, with Li substituting Cu(II).
• Understanding its electronic segregation and the role of Li is crucial for novel electronic materials.

Purpose of the Study:

• To investigate the electronic structure and charge transport properties of LiCu3O3.
• To elucidate the impact of Li substitution and disorder on the material's insulating ground state.
• To explore the resilience of electronic subsystems to impurity scattering.

Main Methods:

• Angle-resolved photoemission spectroscopy (ARPES) to probe electronic band structures.
• Density functional theory (DFT) calculations for first-principle analysis.
• Analysis of charge transport phenomena, including Coulomb gap and spectral weight suppression.

Main Results:

• Two distinct insulating electronic subsystems were identified: a valence band (VB) on the Cu(I) plane and a Zhang-Rice singlet (ZRS) on the Cu(II)O planes.
• Li substitution stabilizes the insulating state, contingent on antiferromagnetic correlations.
• Li-induced disorder leads to 2D electron glass behavior, a large Coulomb gap, and VB spectral weight suppression, while the ZRS remains largely unaffected.

Conclusions:

• Li substitution locally segregates Li and Cu atoms, preserving the electronic integrity of the ZRS.
• The entangled two-hole Zhang-Rice singlet entity exhibits remarkable resilience against impurity scattering.
• This study highlights a unique mechanism for stabilizing electronic subsystems in mixed-valence cuprates.