Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011, USA.
J Phys Condens Matter. 2013 Sep 4;25(35):355702. doi: 10.1088/0953-8984/25/35/355702. Epub 2013 Aug 5.
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 (<3%) of the total doping-induced charge carriers (electrons) are itinerant on the electron lattice made up with the rest of the electrons (>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.
我们解决了在已发表的 La2-xSrxCuO4 单晶的远红外反射率数据中没有涉及电荷有序的远红外特征的问题，而其他实验探针表明电荷有序是超导 cuprates 的标志。通过将不同小组报告的远红外数据并排直接进行比较，以及与拉曼散射数据进行比较，我们发现这些不一致性源于未能通过将反射率误认为是类似 Drude 的金属反射率来捕捉嵌入 La2-xSrxCuO4 单晶近乎完美的 ab 面远红外反射率中的微妙光谱特征。对接近真实反射率数据的分析表明，在所有掺杂水平下（高达 16%），只有一小部分（<3%）总掺杂诱导载流子（电子）在由其余电子（>97%）组成的电子晶格上巡游。我们得出结论，远红外反射率研究远未准备好构建普遍存在的电荷有序现象及其与高温超导性的关系的连贯图像。
