Our research on MgB2 consisted of a series of surprises, almost all of them very pleasant. When we heard of the announcement of superconductivity in this compound by J. Akamitsu (Jan. 10, 2001) we were shocked and immediately had a series of questions. Could we make this material? Could we confirm this claim? If so, could we shed light onto the mechanism of the superconductivity? And could we delineate the basic properties of this compound?

Within a few days we were able to answer the first several questions. We very rapidly developed a simple method of synthesizing high-purity MgB2, confirmed the transition temperature of Tc ~ 40 K, and established that this material was probably an extreme example of old-fashioned superconductivity (similar to other superconductors made up of metallic elements and different from the copper-oxide high-Tc compounds). We then developed a form-preserving synthesis route for turning boron of a specific form into MgB2 with a similar form: e.g., we found that if we take a boron fiber (commercially available) and expose it to Mg vapor we could turn it into a MgB2 wire segment. In a similar manner we could take a thin film of boron and turn it into a thin film of MgB2. This discovery allowed us to continue our research into the basic properties of this compound and also made it very clear (within a month of the discovery of superconductivity) that MgB2 may have significant potential as an applied material.

I suspect that the greatest surprises about MgB2 was the speed at which our (humanity’s) understanding of the superconducting state grew: day by day (with Web postings of papers) rather than week by week or month by month. The second surprise about MgB2 was that it has been a known compound for over 50 years with its superconductivity almost being discovered in the late 1950’s. In some sense MgB2 is a poster child for how far the field of solid state physics has come and, at the same time, for how much more we have to learn about the materials around us.

A vital role! Our research group is part of both the Department of Physics and Astronomy at Iowa State University (ISU) as well as the Condensed Matter Physics program of Ames Laboratory (a Department of Energy Laboratory located on the campus of ISU). The D.O.E. and Ames Laboratory have a long history of supporting new materials research. Ames Laboratory has an over 50-year tradition of strong interactions between physicists, chemists, and metallurgists, and has excellent facilities for the design, synthesis, characterization, and theoretical modeling of novel compounds.

There is also a great deal of flexibility when it comes to chasing new ideas or materials. Within two days of hearing the rumor of superconductivity in MgB2 we were dedicating most of our efforts toward understanding this simple compound. Within about four days we had measured the isotope effect in MgB2, thereby establishing the mechanism of superconductivity, and within four weeks we had three different papers about MgB2 accepted for publication in Physical Review Letters, as well as several other papers posted on the web. Our ability to respond so promptly is primarily due to the support and encouragement of D.O.E., Office of Basic Energy Sciences.

The field of new materials research is wide open. It involves scientists from a broad range of traditional disciplines (traditional departments in universities): physicists, chemists, metallurgists, and materials scientists to name a few. Over the past decades much (but not all) of the exciting discoveries in solid state physics have been associated with the discovery of new materials (or materials properties). We (humanity) have only a moderate knowledge of the properties of simply binary compounds (as illustrated by MgB2 itself) and a very limited knowledge of ternary, quaternary, and more complex compounds. These materials will be the ones that will provide us the improved structural, electronic, magnetic, etc. compounds of the future. The challenge is two-fold: to design/discover, characterize, and understand the basic physics of novel materials and novel groundstates; and to use this understanding to try to design/discover compounds that will be useful for real applications.

In the case of MgB2 there is the very real likelihood that wires of this material will be used to make superconducting electromagnets that will produce the magnetic fields for machines such as the MRI (magnetic resonance imaging) devices found in many hospitals. In addition there is also the hope that MgB2 will prove to be useful for electronic applications as well. There are several advantages that MgB2 has over traditional superconductors. First of all, a transition temperature of 40 K means that it will be useful when cooled to temperatures near 20 K. Whereas this is still a very low temperature (about –250 C) it is fairly easily reached by closed cycle refrigeration. This means that superconducting devices made from MgB2 could be cooled without the need for liquid cryogens. In addition MgB2 has a very low mass density (it’s lightweight) and it has a very low electrical resistivity in the non-superconducting state.

MgB2 does have a lower transition temperature than some of the oxide-based, high-Tc, superconductors, but since MgB2 appears to be a simple, old-fashioned superconductor (with a rather high Tc) it is much easier to work with and appears easier to manipulate.

One important thing to keep in mind is that superconductivity in MgB2 has only been known for about 18 months. There is a lot of applied research yet to be done that will determine whether this will truly be a "useful" material. Right now things do look promising, but time will tell.

Having to judge other people’s work as part of review boards or committees. This task requires care and honesty and is difficult because it involves people’s careers, funding, and/or egos.

• Answering questions, often via design, execution and analysis of experimental measurements.
• Seeing my students and/or post-docs learn, grow, and do well.

To spend time with my family and enjoy their company.

Dr. Paul C. Canfield
Iowa State University, Department of Physics
Ames Laboratory, U.S. Department of Energy
Ames, IA, USA