YOU鈥橵E got to talk fast to make it in the high-pressured world of
superconductors. This week 79 physicists had just two minutes each to describe
their latest work at a hastily arranged session of the American Physical
Society鈥檚 meeting in Seattle. The trigger was the discovery this year of a new
superconducting material, magnesium diboride, that appears to work like ordinary
metal superconductors but at higher temperatures.
Two minutes is just enough time to claim a piece of the action, says George
Crabtree of Argonne National Laboratory in Illinois. 鈥淚t鈥檚 a way to advertise
what you have,鈥� he says.
Only Jun Akimitsu of Aoyama Gakuin University in Japan was given more time.
It was Akimitsu who announced on 10 January that the common laboratory chemical
magnesium diboride could conduct electricity without
resistance at temperatures up to 39 kelvin
(快猫短视频, 3 March, p 6).
Many people had previously thought it impossible for a simple material like this
to have such a high 鈥渃ritical temperature鈥�.
Advertisement
Monday鈥檚 session in Seattle harked back to 1987 and the 鈥淲oodstock of
Physics鈥� in New York City, when 51 researchers reported results on the then new
high-temperature superconductors. These compounds, complex ceramics such as
yttrium-barium-copper oxide, work at temperatures up to 130 kelvin, but cannot
carry much current and are difficult to work with. Researchers have shown,
however, that the electrons within them behave differently from electrons in
ordinary metal superconductors.
Magnesium diboride holds out huge promise because it is easier to work with
and should be able to carry more current.
The latest results suggest magnesium diboride works much like its simpler
metallic cousins. In ordinary superconductors, quantised vibrations, called
phonons, bind electrons into pairs that surf through the material on a phonon
wave. Phonons appear to provide the necessary glue in magnesium diboride, too,
says Warren Pickett of the University of California, Davis. The new material
pushes 鈥渆lectron-phonon coupling鈥� to a surprisingly high temperature, he says.
But it doesn鈥檛 contradict this decades-old theory, as some have claimed.
Alexander Balatsky of Los Alamos National Laboratory in New Mexico advised a
measure of caution. 鈥淚 remember the beginning of high-temperature
superconductors,鈥� he says. 鈥淭here were a lot of misleading results, and it
wasn鈥檛 because people were trying to be misleading, it was because the
experiments were done in a rush.鈥�
But many remain optimistic that the preliminary results on magnesium diboride
will hold. The material has a very simple crystal structure, says Paul Canfield,
a physicist at Iowa State University in Ames. 鈥淚t鈥檚 a very amenable material,鈥�
he says. 鈥淵ou couldn鈥檛 ask for something friendlier.鈥�
