Assistant Professor of Physics
Ph.D. Physics, 1999, University of California, Berkeley
M.S. Physics, 1997, University of California, Berkeley
B.A. Physics, 1992, University of Pennsylvania
B.S. Electrical Engineering, 1992, University of Pennsylvania
Experimental Condensed Matter Physics
Office: 3034 Physics Building
Voice: (909) 787-5343
Fax: (909) 787-4529
A central theme of our research is to develop a fundamental understanding of electron spin and magnetism in nanostructures-solids with physical structure on the nanometer scale. At this length scale quantum effects and interfacial phenomena dominate, leading to behavior not seen in bulk materials. Harnessing these new phenomena for emergent technologies such as spin-electronics and quantum computation requires an understanding of (1) how electron spin interacts with its local environment defined by magnetic, electronic and structural properties (2) how to control these interactions through appropriate manipulation of the structure at the nanometer scale.
We aim to develop new types of hybrid structures consisting of vastly different materials: magnetic semiconductors and metals, epitaxial oxides, nanotubes, molecular crystals, etc. In addition to combining the strengths of the constituents materials, these structures could generate new physical phenomena at the heterointerfaces and may allow for "lab-on-a-chip" experiments of basic physical principles. Advanced materials synthesis techniques (molecular beam epitaxy and self-assembly, optical/e-beam lithography, chemical synthesis) enable the design of materials at the atomic level and the fabrication of physical structure at the nanometer scale.
To investigate the behavior of electron spin within these nanostructures, we employ a variety of techniques including Kerr magnetometry, magnetotransport, synchrotron spectroscopies, and ultrafast optical microscopy. The latter technique enables imaging of spin-, magnetization-, and lattice-dynamics with micron spatial resolution and ~100 fs temporal resolution. In special cases, these techniques can be performed in situ-during the actual construction of the nanostructure.
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)