Implications of charge ordering in high Tc cuprate superconductors in far-infrared spectroscopy

• Published in: Journal of physics. Condensed matter 2013-09, Vol.25 (35), p.355702-355702
• Main Authors: Kim, Y H, Hor, P H
• Format: Article
• Language: English
• Subjects: Computer Simulation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Copper - chemistry; Electronic structure; Exact sciences and technology; Models, Chemical; Models, Molecular; Physics; Properties of type I and type II superconductors; Semiconductors; Spectrophotometry, Infrared - methods; Static Electricity; Superconductivity; Temperature; Thermal Conductivity
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/25/35/355702

We addressed the issue of the absence of far-infrared signatures pertaining to charge ordering in the published far-infrared reflectivity data of La2−xSrxCuO4 single crystals while other experimental probes reveal that charge ordering is a hallmark of superconducting cuprates. Through direct comparison of the far-infrared data reported by various groups side by side and also with the Raman scattering data, we found that the inconsistencies stem from the failure in capturing delicate spectral features embedded in the close-to-perfect ab-plane far-infrared reflectivity of La2−xSrxCuO4 single crystals by misidentifying the reflectivity as the Drude-like metallic reflectivity. The analysis of the close-to-true reflectivity data reveals that only a small fraction (97%) at all doping levels up to 16%. We conclude that the far-infrared reflectivity study is far from being ready to construct a coherent picture of the ubiquitous charge ordering phenomenon and its relationship with the high Tc superconductivity.