Correlation between Raman sum and optical conductivity sum in La2−xSrxCuO4

• Published in: Journal of physics. Condensed matter Vol. 25; no. 41
• Main Authors: Sugai, S, Nohara, J, Shiozaki, R, Muroi, T, Takayanagi, Y, Hayamizu, N, Takenaka, K, Okazaki, K
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 16.10.2013; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties; Physics; Properties of type I and type II superconductors; Superconductivity; Copper Lanthanum Strontium Oxides Mixed; Raman spectra; Electronic structure; Reflection spectrum; High-Tc superconductors; Strongly correlated electron systems; Spectral functions; Two magnon process; Infrared spectra; Absorption coefficients; Carrier density; Optical conductivity
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/25/41/415701

In a strongly correlated electron system, the single-particle spectral function changes into a coherent peak and incoherent humps which extend over 1 eV. The incoherent parts lose the symmetry and k dependence, so that the Raman spectra with different symmetries become identical and they are expressed by the optical conductivity. We found that the B1g and B2g spectra in La2−xSrxCuO4 become identical above 2000 cm−1 in the underdoped phase, if Fleury-Loudon type B1g two-magnon scattering is removed. The first Raman susceptibility moment correlates with the generalized optical conductivity moment. The good correlation arises from the incoherent states of a hump from 1000 to 4000 cm−1. The hump is the only structure of the incoherent electronic states in the mid-infrared absorption spectra below 1.4 eV at low carrier densities. The energy is twice the separated dispersion segments of the spin wave in the k stripe direction. The incoherent state is formed by the magnetic excitations created by the hole hopping in the antiferromagnetic spin stripes in the real space picture.