A recent analysis of scientific papers on superconductivity by researchers at Fachinformationszentrum Karlsruhe (FIZ) and the Max Planck Institute for Solid-State Research has sparked animated discussion in the superconductivity community. One conclusion drawn by the study, which was intended to offer a new tool for scientists evaluating possible directions for research, is that the field of superconductivity research will be essentially empty by 2015.

Andreas Barth at FIZ and Werner Marx at Max Planck used publication databases to analyze the body of research on cuprate high-Tc superconductors for the occurrence of specific elements and compounds. The researchers’ intention was to demonstrate exciting possibilities of chemical databases and information mining in order to provide a different view from experimental or theoretical research on highly complex and information-dense areas such as HTS.

“The large number of new superconducting compounds and related articles has caused scientists working in this research field to have increasing problems in overviewing their discipline and staying up-to-date with the new literature,” stated Marx. “Even more problematic is the fact that it becomes more and more difficult to integrate the new work into the existing body of information and knowledge.

“The reason for carrying out this study was to demonstrate the potential of modern databases and search systems for generating meta-information interesting for scientists working in a specific field. We analyzed the family of cuprates in order to identify characteristic patterns. Our compound maps reveal known and unknown compounds, together with the associated numbers of registered species. These maps enable researchers to detect white spots and to identify research potential for the preparation and analysis of unknown compounds.”

Barth and Marx also searched the INSPEC and the Chemical Abstracts Service databases for papers with “supercond“ in the abstract or title, and compared the results from 1955 to the present. The researchers found that interest in the field increased significantly in the late 1980s, following the discovery of HTS by Georg Bednorz and Alex Müller at IBM’s Zurich lab in 1986. The peak in papers came around 1990, with 8,500 papers in the INSPEC database that year, compare to 4,400 now. By linearly extrapolating this decline in numbers, Barth and Marx concluded that no research papers will be published about superconductivity by 2010 or 2015.

Paper’s Authors Question Death of Superconductivity Interpretation

Based on the Barth and Marx paper’s prediction, an article entitled “Slow death for a dying topic”, by Matin Durrani (Physics World, September 2006), has stirred up considerable public discussion about future of superconductivity research. (The Durrani article contrasts starkly to the selection of HTS as one of eight “Areas to Watch in 2006” by the editors of Science magazine last December.) Indeed, some leaders in the field have questioned the validity of the methods used by Barth and Marx. However, Barth and Marx have distanced themselves from the more extreme assertions highlighted in the Durrani article.

“Linear extrapolations to the future are always problematic,” commented Marx. “The words ‘zero’ (used by us to indicate the size of the decrease in cuprate based publications) and ‘death’ (used by others in their comments about the entire field) are not fully adequate expressions here—they should certainly not be taken literally.

Marx said he believed a considerable amount of superconductivity research can be expected in the future, provided new groundbreaking discoveries happen to occur or new applications are developed: “The discovery of new superconductors with significantly higher Tc, of an unexpected new superconducting compound class, or a convincing and satisfactory theoretical explanation of the phenomenon would certainly boost the field again.”

Experts Challenge Barth & Marx Study

Paul Grant, Principal of W2AGZ Technologies and Visiting Scholar in Applied Physics at Stanford University, agreed with Marx: “One has to be careful when predicting the death of particular sectors of physics based on publication frequency alone. All fields of condensed matter physics undergo periods of ebb and flow. Some of the best quality research on the physics of organic superconductors occurred well after major efforts in the area had cooled down.”

Paul Chu, Professor of Physics at the University of Houston and Executive Director of the Texas Center for Superconductivity, added: “This paper depends purely on statistics, but the saying popularized by Mark Twain goes, ‘There are three kinds of lies: lies, damned lies, and statistics.’ Simply going by publication numbers, superconductivity should have died many times previously, e.g. in the 1950s, or in the late 80s, when the NSF was thinking about closing down its superconductivity research programs because of the assumption that the interesting results were already over. Even in 1989, in the heyday of HTS, there was a story in Science entitled ‘Superconductivity: Is the Party Over?’ I did not think so, and later facts proved that I was right.”

Grant believes important science remains: “There is still no general agreement on the precise nature of the bosonic glue that pairs the holes in these compounds. The field of superconductivity is wide open, both experimentally and theoretically. At the end of the day, support and funding decisions relevant to basic research choices should rest on quality, not quantity. Prematurely reducing funding based solely on statistics could lead to talent leaving a field just before something big happens, as occurred with superconductivity in the early 1980s.”

Chu believes that the Barth and Marx study is unlikely to affect the directions researchers take in superconductivity, despite its detailed mapping of the field: “Creativity requires a human factor—a systematic, and in particular a statistical, approach usually does not lead to a breakthrough.”

Study Not Aimed at Applied Superconductivity

Marx pointed out that his study was focused on basic research in chemistry and physics and not on engineering and technology: “The more applied the work is, the more incomplete is the coverage in literature databases.”

Nonetheless, the study, the related Durrani article, and the public reaction to both have drawn fire from the industry side of the superconductor community. Greg Yurek, President and CEO of American Superconductor and former Professor at MIT, commented: “Since the focus of the field is shifting from the areas tracked by chemical and physics abstracts to new areas, particularly in applications, a better measure of the vibrancy of the superconductivity field is the total number of papers at conferences—which is continuing to grow year after year.

“The real research drivers are the grand challenges of the superconductivity field: the theory of HTS, the search for new materials through increasingly powerful simulation and characterization tools, and the practical challenge of understanding and predicting HTS supercurrent limits. The main surge of activity taking place right now is focused on commercializing a vast array of applications.”

“Superconductor applications, and possibly even basic research, still have a bright future. This study should have little impact on applications of HTS and the HTS industry. It can be well expected that basic research activity in a field with technical implications is decreasing after a decade or so, and is shifting to applied science and engineering.”

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