Optical response of correlated electron systems

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Experimental techniques now allow detailed analysis of carrier dynamics in correlated electron materials via optical conductivity.
• Understanding optical response is crucial for characterizing electron behavior in complex materials.

Purpose of the Study:

• To review and analyze the role of momentum relaxation in optical conductivity.
• To examine the [Formula: see text] scaling of optical conductivity in Fermi-liquid metals.
• To investigate the optical conductivity of non-Fermi-liquid metals, particularly near quantum phase transitions.

Main Methods:

• Analysis of electron-electron scattering (normal and umklapp processes).
• Revisiting the Gurzhi formula and its implications for optical scattering rates.
• Investigating scattering mechanisms, including elastic and energy-dependent types.
• Theoretical modeling of metals near quantum phase transitions (nematic, spin-density-wave).

Main Results:

• Optical conductivity in a two-band metal does not strictly follow the Drude formula.
• Deviations from Gurzhi scaling ([Formula: see text]) are observed, potentially due to energy-dependent scattering.
• Non-Fermi-liquid behavior in optical conductivity is identified near spin-density-wave transitions, with distinct low- and high-frequency scaling.

Conclusions:

• Momentum relaxation and scattering processes significantly impact optical conductivity in correlated electron materials.
• The study provides insights into deviations from Fermi-liquid theory and highlights non-Fermi-liquid characteristics.
• This review synthesizes current understanding and theoretical approaches to optical conductivity in advanced materials.