Three-Dimensional Fermi Surface of Overdoped La-Based Cuprates

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• High-temperature superconductors, particularly cuprates, exhibit complex electronic properties.
• Understanding the Fermi surface and electronic density of states is crucial for explaining their behavior.
• Overdoped La$_{2-x}$Sr$_{x}$CuO$_{4}$ shows an unusually large electronic specific heat.

Purpose of the Study:

• To investigate the Fermi surface topology and electronic structure of overdoped high-temperature superconductors.
• To determine the contribution of the van Hove singularity to the electronic specific heat.
• To explore alternative explanations for the enhanced electronic specific heat.

Main Methods:

• Soft x-ray angle-resolved photoemission spectroscopy (SX-ARPES).
• Mapping of in-plane and out-of-plane Fermi surface components by varying photon energy and detection angle.
• Tight-binding parametrization for electronic structure analysis.

Main Results:

• No k$_{z}$ dispersion was observed along the nodal direction of the Fermi surface.
• Significant antinodal k$_{z}$ dispersion was identified in La-based cuprates.
• The van Hove singularity alone cannot account for the large electronic specific heat.

Conclusions:

• The electronic specific heat enhancement in overdoped La$_{2-x}$Sr$_{x}$CuO$_{4}$ likely stems from factors beyond the van Hove singularity.
• Quantum criticality, driven by a collapsing pseudogap phase, is proposed as a plausible mechanism.
• This finding offers new insights into the exotic electronic states in high-temperature superconductors.