Superconductivity in MgB₂

Professor J. Akimitsu (Aoyama Gakuin University) announced the discovery of superconductivity in MgB₂ at 39 K on January 10, 2001, at a symposium on "Transition Metal Oxides" in Sendai, Japan. This discovery stimulated a considerable amount of research and development concerning MgB₂, not only because of its interesting fundamental properties but also because of its potential applications. At the end of January 2001, we set aside a special section (MgB₂ Preprint List) for preprints related to superconductivity in MgB₂. The following table showing the number of MgB₂-related preprints by month is a measure of interest in this material during 2001-03. [As noted in the announcement on our home page (http://www.iitap.iastate.edu/htcu/), we will be unable to cover new developments after December 31, 2003.]

The 9 papers in the December preprint list span the range from fundamental to applied.

A preprint by T. M. Mishonov et al. reports that the weak-coupling anisotropic BCS theory provides a good description of the measured energy gap and specific heat of MgB₂.

The effect of preparation conditions upon the transport properties of bulk and thin-film MgB₂ superconductors is reported by V. A. Drozd et al. A. Agliolo Gallitto et al. report measurements of the magnetic-field dependence of the microwave response of ceramic MgB₂ samples. Kh. A. Ziq reports measurements at different temperatures showing that the critical current density J_c scales with the bulk thermodynamic critical field H_c.

Several preprints in this listing report experiments on the effects of carbon doping of MgB₂. T. Masui et al. report on the effect of carbon substitution on the electronic properties of MgB₂ single crystals. E. Ohmichi et al. reports on an enhancement of the irreversibility field by carbon substitution in single-crystal MgB₂. M. Pissas et al. report on the influence of carbon doping upon vortex-matter properties in MgB₂. R.H.T. Wilke et al. report experiments showing how carbon doping enhances the upper critical field H_c2, increases the resistivity at 40 K, and depresses the transition temperature T_c of MgB₂.

A paper by M. Fu et al. reports measurements of the minimum quench energy and normal-zone propagation velocity in MgB₂ superconducting tape.

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Following is further background material regarding MgB₂. Professor J. Akimitsu (Aoyama Gakuin University) announced the discovery of superconductivity in MgB₂ at 39 K on January 10, 2001, at a symposium on "Transition Metal Oxides" in Sendai, Japan. He provided us with three figures, which show:

(1) The crystal structure of MgB₂

(2) The magnetic susceptibility as a function of temperature, and

(3) The temperature dependence of the resistivity.

The paper describing the details, J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, and J. Akimitsu, "Superconductivity at 39 K in MgB₂," Nature 410, 63 (2001), is available at

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v410/n6824/full/410063a0_fs.html

or by browsing Nature's Physics Portal, http://www.nature.com/physics/ (click on "research highlights" and register to get password for free membership). An interesting account of recent developments leading towards applications can be found at

http://www.nature.com/physics/physics.taf?file=/physics/highlights/6837-2.html.

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There was a special session on MgB₂ at the APS 2001 March Meeting in Seattle. You may view the program and download recordings of talks and reproductions of accompanying viewgraphs at http://www.aps.org/meet/MAR01/mgb2/.

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Related articles by:

John Rowell, http://www.iitap.iastate.edu/htcu/rowellcomment.html

Marty Nisenoff, http://www.iitap.iastate.edu/htcu/nisenoffcomment.html and

Paul Grant http://www.iitap.iastate.edu/htcu/grantcomment.html

give the authors' assessments of the potential of MgB₂ for small-scale and large-scale applications, based on the information available at the time of the 2001 March Meeting. (Click on the above to see their comments.)

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The following news accounts are available:

February 2, 2001, Physics World, “Metal superconductors reach new high,” by Katie Pennicott:
http://www.physicsweb.org/article/news/05/2/3

February 13, 2001, Physics News Update, "All-metal Superconductivity at 40 K," by Phil Schewe, James Riordon, and Ben Stein:
http://www.aip.org/physnews/update/526-1.html

February 14, 2001, Neue Zürcher Zeitung, "Ein übersehener Supraleiter," by Christian Speicher:
http://www.nzz.ch/2001/02/14/ft/page-article75XTG.html

February 24, 2001, New York Times, "Physicists Thrill to Finding of Superconductor," by Kenneth Chang:
http://www.nytimes.com/2001/02/24/science/24SUPE.html?searchpv=site04

February 24, 2001, Washington Post, "Superconductor Gain Holds Promise of Energy Efficiency," by Guy Gugliotta:
http://www.washingtonpost.com/wp-dyn/articles/A47832-2001Feb23.html

March 5, 2001, Ames Lab Press Release, "Ames Lab Research Leads to Better Understanding of New Superconducting Compound," by Saren Johnston:
http://www.ameslab.gov/news/release/superconducting.htm

April 1, 2001, Physics World, “New metallic superconductor makes an immediate impact,” by Colin Gough:
http://www.physicsweb.org/article/world/14/4/2

June 6, 2001, GlobalTechnoScan.com, "Improving industrial prospects for new superconductor MgB2," by Judith H. Moore http://www.globaltechnoscan.com/6thJune-12thJune01/superconductor.htm

June 11, 2001, New York Times, "Researchers Turn Compound into Superconducting Wires," by Kenneth Chang
http://www.nytimes.com/2001/06/11/science/11SUPE.html

January 1, 2002, Physics World, "Magnesium diboride: one year on," by Paul C. Canfield and Sergey L. Bud'ko [for full article, see Physics World 15, 29 (2002)]: http://www.physicsweb.org/article/world/15/1/10

February 1, 2002, Science, “MgB₂ Trades Performance for a Shot at the Real World,” by Robert F. Service [for full article, see Science 295, 786 (2002)]: http://www.sciencemag.org/cgi/content/summary/295/5556/786

June 17, 2002, Brookhaven National Laboratory press release, “New Insight Into Origin of Superconductivity in Magnesium Diboride,” by Patrice Pages
http://www.bnl.gov/bnlweb/pubaf/pr/2002/bnlpr061702.htm

August 8, 2002, Materials Update, “August 2002: Magnesium diboride,” by Ed Gerstner
http://www.nature.com/cgi-taf/Gateway.taf?g=3&file=/materials/month/articles/m020808-7.html

August 14, 2002, Physics Web, “Magnesium diboride: mind the gaps”
http://physicsweb.org/article/news/6/8/9

August 15, 2002, Nature, “Superconductivity: Mind the double gap,” by Warren Pickett [News and Views article in Nature 418, 733 (2002)]
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v418/n6899/full/418733a_fs.html

September 3, 2002, New York Times, “Rapid New Understanding of Superconducting Compound,” by Kenneth Chang
http://query.nytimes.com/search/abstract?res=F30A15FF355B0C708CDDA00894DA404482

October, 2002, Thomson ISI, “Magnesium Diboride Superconductors.” Drawing upon its citation database for 1992 - May 2002 (438 papers, 1331 authors, 44 countries, 63 journals, and 309 institutions), ISI provides a listing of the top 25 papers, authors, institutions, nations, and journals, and also includes interviews and further information about MgB2.
http://www.esi-topics.com/mgb2/

March, 2003, Physics Today, "Magnesium Diboride: Better Late than Never," by Paul C. Canfield and George W. Crabtree
http://www.physicstoday.org/vol-56/iss-3/p34.shtml

May 1, 2003, Physics Web, "Magnesium diboride at the double," by Belle Dumé
http://physicsweb.org/article/news/7/5/1

By John R. Clem, Science Consultant