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Correlation between Raman sum and optical conductivity sum in La(2-x)Sr(x)CuO4
S Sugai1, J Nohara, R Shiozaki
1Department of Physics, Arts and Science, Petroleum Institute, PO Box 2533, Abu Dhabi, UAE. Department of Physics, Faculty of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|September 24, 2013
Summary
In strongly correlated electron systems, Raman spectra reveal incoherent electronic states. These states, linked to magnetic excitations in spin stripes, correlate with optical conductivity.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spectroscopy
Background:
- Strongly correlated electron systems exhibit complex electronic behaviors, including the transformation of single-particle spectral functions into coherent peaks and incoherent humps.
- These incoherent parts often lose symmetry and momentum (k) dependence, leading to similarities in Raman spectra of different symmetries.
Purpose of the Study:
- To investigate the relationship between Raman spectra and optical conductivity in strongly correlated electron systems.
- To analyze the nature and origin of incoherent electronic states in materials like La(2-x)Sr(x)CuO4.
- To explore the role of magnetic excitations in forming these incoherent states.
Main Methods:
- Raman spectroscopy measurements on La(2-x)Sr(x)CuO4.
- Analysis of spectral functions and optical conductivity.
- Removal of Fleury-Loudon type B1g two-magnon scattering for spectral comparison.
- Moment analysis of Raman susceptibility and optical conductivity.
Main Results:
- Raman spectra of different symmetries (B1g and B2g) in La(2-x)Sr(x)CuO4 become identical above 2000 cm(-1) in the underdoped phase after accounting for magnon scattering.
- A strong correlation was observed between the first Raman susceptibility moment and the generalized optical conductivity moment.
- This correlation is attributed to incoherent electronic states forming a hump (1000–4000 cm(-1)) in the mid-infrared absorption spectra.
- The hump's energy is approximately twice the spin wave dispersion segments in the k(perpendicular) stripe direction.
Conclusions:
- The incoherent electronic states in strongly correlated systems are significantly influenced by magnetic excitations within antiferromagnetic spin stripes.
- Hole hopping in these spin stripes is a key mechanism for forming these incoherent states.
- Raman spectroscopy, when analyzed in conjunction with optical conductivity, provides insights into the complex electronic and magnetic properties of these materials.
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