Science magazine published a technical comment of Skoltech professor Boris Fine on an article of Canadian and German scientists about high-temperature cuprate superconductors.
Superconductivity was discovered in cuprates by Bednorz and Müller in 1986 (Physics Nobel Prize in 1987), but the mechanism of this phenomenon is still hotly debated by physicists. The original article reported the results of resonant X-ray scattering experiments investigating spontaneous modulations of electronic charge density, which were known to exist in cuprates and widely expected to exert an important influence on the superconductivity mechanism. The article aimed at resolving the fundamental issue of whether the modulations are one-dimensional stripe-like or two-dimensional checkerboard-like. The implications of these two propositions for the superconductivity mechanism are quite different. The issue has been debated in the cuprate community for over 20 years, still without a conclusive resolution. The experimental results presented in the article were interpreted by the authors as providing “clear evidence for the unidirectional (stripe) intrinsic nature” of the charge modulations. Boris Fine disagreed. He pointed out in his comment that the experimental results are also consistent with a checkerboard, of which he produced an example. The authors in their response insisted on their original conclusions arguing that the checkerboard produced by Boris Fine exhibits a high degree of “stripiness”. “The reviewers and the editors of Science magazine decided that this is a healthy discussion, about which the readers should be informed to form their own opinion,” says Boris Fine. “This is how scientific process normally works.”
Superconductivity is a quantum phenomenon discovered in 1911 by the group of Dutch physicist Kammerling-Onnes. It manifests itself through a complete disappearance of electrical resistance accompanied by the expulsion of magnetic field from the material. Originally, the superconductivity was observed only in some simple metals, such as mercury or aluminum, at temperatures of only a few degrees Kelvin above the absolute zero (-273°C). The so-called “high-temperature superconductors” become superconducting at significantly higher absolute temperatures of the order of 100 Kelvin (-173°C), but these temperatures are still freezingly low if compared to the room temperature. Despite the need to cool them down, superconductors are already used today in various devices such as, for example, high-sensitivity magnetometers or high-field magnets for magnetic resonance tomography. Yet, many scientists are searching for materials that become superconducting at room temperatures, because, if found, such materials are likely to make revolutionary technological impact, in particular, in electronics and power transmission. Boris Fine remarks: ‘The interest in the mechanism of superconductivity in cuprates is, to a large extent, motivated by the hope that, if understood, it can guide the search for room-temperature superconductors.”
Original paper: http://science.sciencemag.org/content/347/6228/1335?ijkey=bbba88757b0da77f57770ffa5125288c68b36cba&keytype2=tf_ipsecsha
Boris Fine’s comment: http://science.sciencemag.org/content/351/6270/235.1.full
Authors’ response to the comment: http://science.sciencemag.org/content/351/6270/235.2
* The Skolkovo Institute of Science and Technology (Skoltech) is a private graduate research university in Skolkovo, Russia, a suburb of Moscow. Established in 2011 in collaboration with MIT, Skoltech educates global leaders in innovation, advances scientific knowledge, and fosters new technologies to address critical issues facing Russia and the world. Applying international research and educational models, the university integrates the best Russian scientific traditions with twenty-first century entrepreneurship and innovation.
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