Experimental condensed matter physics
of rare-earth and transition metal magnets.
A short introduction can be found here.
Rare-earth based thin films
and nanoscale particles were prepared by several methods. Sputter deposition, magnetic
measurements, and structural characterization facilities were built up over
many years in my lab and in collaboration with other condensed matter
physicists in the K-State physics department.
This work has been published in leading refereed international
journals including Physical Review Letter, Physical Review B, Journal of
Applied Physics, Journal of Magnetism and Magnetic Materials, and European
Journal of Physics. Work in my
Thin film and
bulk nanostructured magnets based on Nd2Fe14B and
SmCo5 were prepared by sputtering. Structure and magnetic properties
including coercivity and energy product were correlated. See here for a discussion of size effects. The effect of size of the magnetic layers or
particles, and the effect of an anneal in the presence of a magnetic field
were examined. See here and
an overview of this work.
superconductivity and the effects of neutron irradiation were studied in
several high temperature superconductors including YBa2Cu3O7-x. We were able to improve critical current values
with the neutron irradiation.
possibility of quantum mesoscopic tunneling was examined in several thin
film rare-earth alloys with strong magnetic anisotropy. Indirect evidence for such tunneling was
found in several of these systems.
of random magnetic anisotropy on phase transitions and critical phenomena
was studied at reduced temperatures down to down to 6 ´ 10-5. In
particular scaling in ferromagnetic systems and systems with strong random
anisotropy were tested in this small reduced temperature range. Interesting crossovers were seen as a
function of the ratio of anisotropy/exchange strength and as a function of
Parts of the above
work were supported by grants from the National Science Foundation, the Army
Research Office, and NATO.