Intrinsic temperature-dependent evolutions in the electron-boson spectral density obtained from optical data

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Optical data analysis of high-temperature superconductors often involves complex spectral functions.
• Understanding electron-boson interactions is crucial for explaining material properties.
• Maximum Entropy Method (MEM) is a key technique for extracting spectral information.

Purpose of the Study:

• To investigate the impact of temperature smearing on the electron-boson spectral density function (I(2)χ(ω)).
• To assess the robustness of extracted spectral properties under varying data quality and temperature effects.
• To determine if optical data from cuprates exhibit intrinsic temperature-dependent evolutions.

Main Methods:

• Utilized a Maximum Entropy Method (MEM) for inverting optical scattering rates to obtain the spectral density function.
• Employed model input spectral density functions and a generalized Allen's formula to simulate optical scattering rates at different temperatures.
• Applied MEM to optical data from optimally doped and underdoped cuprates.

Main Results:

• The inversion process accurately recovers input spectral density functions when data quality is high.
• Temperature smearing effects become apparent in the spectral density function with lower data quality.
• The coupling constant and logarithmically averaged frequency demonstrate robustness against temperature smearing and data quality variations.

Conclusions:

• Extracted electron-boson spectral density functions from optical data of cuprates show intrinsic temperature-dependent evolutions.
• Robustness of certain spectral parameters can serve as a criterion to identify genuine temperature effects in experimental data.
• The study validates the application of MEM for analyzing optical properties of complex materials like superconductors.