Physics graduate student Stephen Wilson has been
honored for his efforts to understand the basic principles driving
high-temperature superconductivity. The Topical Group on Magnetism
and Its Applications (GMAG), a sub group of the American Physical
Society, has named him a winner of the 2006-2007 GMAG Student Dissertation
Award. The accolade includes a $500 prize and an opportunity to present
an invited talk at the APS March meeting in Denver.
Scientists have long known that superconductivity results from
the pairing of electrons, which allows electric current to pass
through a material with no resistance. Yet a satisfactory explanation
of exactly what binds those electron pairs at high temperatures
(high-Tc) has yet to be discovered. In his dissertation work, Wilson
uses neutron scattering to get a more precise picture of how high-Tc
materials are structured and what properties give rise to their
superconductivity. Neutrons are an excellent probe because they
are highly penetrating and pass easily through the bulk of materials,
and they are sensitive to both structure and static/dynamic magnetism
in the system.
Wilson studied the cuprate Pr.88LaCe.12CuO4-d,
a typical superconductor. Cuprates are ceramic compounds containing
elements of metal sandwiched between layers of copper and oxygen
atoms. They become superconducting when they are “doped”
with a carrier; either electrons or holes (vacant electron positions).
Wilson used neutrons to probe the behavior of the material’s
spin—an intrinsic property, the same as charge or mass. While
earlier spin studies have shown that magnetism may play a key role
in electron pairing in hole-doped materials, little research has
been done on the electron-doped superconductors. Using neutron scattering
to reveal the spin behavior of the electron-doped Pr.88LaCe.12CuO4-d,
Wilson found that magnetic resonance seems to be a unifying fundamental
feature among the cuprates, regardless of the doping carrier type.
Another part of his dissertation involves studying the spin dynamics
in the alloy Sc1-xUxPd3.
Wilson earned a bachelor’s degree in physics at UT in 2002
and subsequently enrolled in the physics graduate program. He joined
Professor Pengcheng Dai’s research group in 2003 and in 2005
he won the department’s Paul H. Stelson Fellowship in Physics
for Outstanding Beginning Research. He was the lead author on “Resonance
in the electron-doped high-transition-temperature superconductor
Pr0.88LaCe0.12CuO4-d,;
which appeared in the July 6 issue of Nature.
