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Roland Kawakami
Assistant Professor of Physics
Ph.D. 1999, University of California, Berkeley
Experimental Condensed Matter Physics
E-mail: roland.kawakami@ucr.edu
Phone: (951) 827-5343
Fax: (951) 827-4529
Lab: (951) 827-7141
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A central theme of our
research is to understand the behavior of electron
spin in nanoscale structures and its relation to magnetic and
opto-electronic properties.
At the nanometer length scale quantum effects and interfacial phenomena
dominate, leading to
behavior not seen in bulk materials. Our work focuses on synthesizing
novel
heterostructures and devices consisting of magnetic, semiconducting,
and
organic
materials, and
exploring the
new physics
which emerge in these systems. The development of electronic devices
that
utilize the electron spin has come to be known as "spintronics," and
there is a strong potential for applications in magnetic information storage,
reconfigurable
logic, magnetic
field
sensors,
and
their
integration with display and communication technologies. The new heterostructures
and materials developed in our laboratory might also become important for
spin-based quantum information systems.
Molecular beam epitaxy (MBE) provides
a means for synthesizing thin film heterostructures in an atom-by-atom manner
(or molecule-by-molecule) for the best possible
control over the material and interface structure. In situ scanning
tunneling microscopy (STM) provides atomic-scale structural characterization,
while in
situ optics (including ultrafast optics and magneto-optics) investigates
the dynamics of spin, magnetism, and light emission in these heterostructures.
Combining
these
techniques
with
lithographically-defined
templates enables electronic devices to be fabricated under the same high-quality
MBE growth conditions, and specially-made sample holders allow the devices
to be
tested in situ; this avoids the potentially damaging effects of
air. This new approach to fabricating and testing devices is being used
to develop spintronic devices as well as charge-based optoelectronic devices.
Specific materials of interest include ferromagnetic metals, ferromagnetic semiconductors,
organic semiconductors, and carbon nanotubes. Combinations of these materials
are expected to yield new physical phenomena that do not exist in the individual
materials and thus form a major part of our research. In addition,
the
development
of
half-metallic ferromagnets with high spin
polarization
at
room
temperature is recognized as one of the most important challenges for
spintronic technologies and is part of our long term objectives.
Selected Publications
R. K. Kawakami, Y. Kato, M. Hanson, I. Malajovich, J. M. Stephens,
E. Johnston-Halperin, G. Salis, A. C. Gossard, and D. D. Awschalom, "Ferromagnetic Imprinting of Nuclear Spins in Semiconductors," Science,
294, 131 (2001).
R. K. Kawakami, E. Johnston-Halperin, L. F. Chen, M. Hanson,
N. Guébels, J. S. Speck, A. C. Gossard, and D. D. Awschalom,
"(Ga,Mn)As as a Digital Ferromagnetic Heterostructure," Appl. Phys. Lett. 77,
2379 (2000).
R. K. Kawakami, E. Rotenberg, Hyuk J. Choi, Ernesto
J. Escorcia-Aparicio, M. O. Bowen, J. H. Wolfe, E. Arenholz, Z. Zhang,
N. V. Smith, and Z. Q. Qiu, "Quantum Well States of Cu Thin Films," Nature
398, 132 (1999).
R. K. Kawakami, E. Rotenberg, Ernesto J. Escorcia-Aparicio, Hyuk
J. Choi, T. R. Cummins, J. G. Tobin, N. V. Smith, and Z. Q. Qiu, "Observation of the Quantum Well Interference in Magnetic
Nanostructures by Photoemission," Phys. Rev. Lett. 80, 1754 (1998).
R. K. Kawakami, Ernesto J. Escorcia-Aparicio and Z. Q. Qiu, "Symmetry-Induced Magnetic Anisotropy in Fe Films Grown on Stepped
Ag(001)," Phys. Rev. Lett. 77, 2570 (1996).
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