Eliashberg Theory for Dynamical Screening in Bilayer Exciton Condensation

Area of Science:

• Condensed matter physics
• Materials science
• Quantum mechanics

Background:

• Exciton condensation is a quantum phenomenon relevant to novel electronic devices.
• Understanding interaction screening is crucial for predicting material properties.

Purpose of the Study:

• To investigate the influence of dynamical screening on exciton condensation transition temperatures (T_{c}).
• To compare theoretical predictions with and without screening effects.

Main Methods:

• Solving linearized Eliashberg equations for interlayer Green's functions.
• Utilizing a diagrammatic framework to analyze the system's behavior.

Main Results:

• Finite T_{c} was observed, decreasing exponentially with interlayer separation.
• Dynamical screening suppresses T_{c} below Hartree-Fock predictions but exceeds static screening estimates.
• The system forms an exciton condensate at zero temperature, with T_{c} diminishing at large separations.

Conclusions:

• Dynamical screening plays a critical role in determining exciton condensation temperatures.
• The findings provide insights into designing materials for exciton-based technologies.