Final Report Page: 3 of 3
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During the duration of this grant our building was renovated, which made it necessary to move
the laboratory out to a temporary location and back to its previous location over a period of nine
months. Adding time for the breakdown and reinstallation of the laboratory and failure of the
integrity of the new floor, our main apparatus, our pulsed magnetic field, was not available for
about a year. During this time we developed the pressure cells and rebuilt parts of the pulsed
magnetic field. All of the digital control electronics were updated with microcontrollers to make
the system more robust and versatile. Also during this time, Si Foner donated the contents of his
laboratory at MIT to us as he went into retirement. Dr. Foner had arguably the world's leading
pulsed magnetic field laboratory, he held the magnetic field record for many years, and having
his magnets to analyze and having his advanced high strength magnet wire has already given us
access technology that is very hard to recreate.
The apparatus that was rebuilt in our laboratory as part of the grant is unique and powerful. In
addition to producing the highest magnetic field outside of Los Alamos, 51 tesla, experiments
can be preformed down to 400 mK, and probably lower with technology developed during the
grant but not yet tested. Just as important, the software and control of the system was optimized
to maximize the data throughput. As an example, in one experiment 195 magnet sweeps in the
range of 10 to 50 tesla were done in a period of 9 days, averaging over 20 magnet sweeps a day.
This level of data collection is not possible with a dc magnet. In addition, in our system only the
sample needs to be cooled with helium, because our magnet is cooled by liquid nitrogen. In
these nine days of experiments only 100 liters of liquid helium were used.
The tunnel diode oscillator system that we use for rf penetration depth measurements was also
improved during this grant. The signal to noise ratio was reduced by a factor of 10. A good
signal to noise ratio is essential to picking out the subtle phase transitions that occur in many
condensed matter systems, and rf penetration is very compatible with pulsed magnetic fields.
Along with its sensitivity to many physical properties, such as vortices, the London penetration
depth, normal skin depth, etc., the tunnel diode system is compatible with pulsed fields because
it tends to run a a frequency much higher than the electrical noise produced by the pulsed
magnetic field. Therefore it is useful for many kinds of high magnetic field experiments. These
attributes have made rf penetration a mainstay of the national pulsed magnetic field facility at
During this grant we discovered an exotic superconducting state, predicted over 40 years ago,
and showed that it will help understand the pairing mechanism of superconductors with magnetic
ions. We built a unique and powerful apparatus for studying condensed matter systems at high
magnetic fields, and shared the technology with a national laboratory. During this time we also
educated graduate and undergraduate scientists.
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Agosta, Charles C. Final Report, report, June 14, 2013; United States. (digital.library.unt.edu/ark:/67531/metadc846544/m1/3/: accessed August 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.