| overview |
My interests include non-equilibrium magnetism in correlated electronic systems, and magneto-optical studies of nanomaterials. Our transient pump-probe research combines femtosecond optical techniques with low-temperature methods to explore the dynamics of spin related phenomena in solids. Optical interactions provide an elegant and powerful probe of angular momentum transfer throughout a broad variety of systems, revealing the flow of spin information from photons to electrons to localized ionic complexes and, ultimately, to nuclei. Our time-resolved work on colossally magnetoresistive manganites has compared spin and charge dynamics and found evidence for photonucleated transitory magnetic ordering using the dynamical magneto-optical Kerr effect.
Much of our work on nanomaterials has focused on carbon nanotubes and involves a variety of spectroscopies including thermal conductivity, electrical percolation and magnetoresistance, polarized linear optical absorbance, photoluminescence, and Raman scattering, and single-tube scanning photoluminescence. Our most recent results include the optical measurement of inter-tube migration of non-equilibrium carriers in bundles of single-walled carbon nanotubes, and the measurement of chirality dependence to the magnetic susceptibility anisotropy in single-walled carbon nanotubes. |
| select pubs |
- P.M. Vora, X. Tu, E.J. Mele, M. Zheng, and J.M. Kikkawa. Chirality dependence of the /K/-momentum dark excitons in carbon nanotubes. Phys. Rev. B, 81: 155123, 2010
- A. Dong, J. Chen, P.M. Vora, J.M. Kikkawa, and C.B. Murray. Binary nanocrystal superlattice membranes self-assembled at the liquid-air interface. Nature, 466: 474-477, July 2010
- Z. Luo, P.M. Vora, E.J. Mele, A.T. C. Johnson, and J.M. Kikkawa. Photoluminescence and band gap modulation in graphene oxide. Appl. Phys. Lett., 94: 111909-111911, 2009
- O. N. Torrens, M. Zheng, and J. M. Kikkawa. Energy of k-momentum dark excitons in carbon nanotubes by optical spectroscopy. Physical Review Letters, vol 101, p. 157401 (2008).
- P.R. Frail, K. Susumu, M. Huynh, J. Fong, J.M. Kikkawa, M.J. Therien, Modulation of Dark Conductivity over a 1 × 10 −12 to 1 × 10−5 S/cm Range Through Ancillary Group Modification in Amorphous Solids of Ethyne-Bridged (Porphinato)zinc(II) Oligomers, Chem. Mater. 19, 6062-6064 (2007).
- O.N. Torrens, D.E. Milkie, H.Y. Ban, M. Zheng, G.B. Onoa, T.D. Gierke, J.M. Kikkawa, “Measurement of Chiral-Dependent Magnetic Anisotropy in Carbon Nanotubes,” Journal of the American Chemical Society 129, 252-253 (2007).
- M. B. Bryning, D. E. Milkie, M. F. Islam, L. A. Hough, J. M. Kikkawa, A. G. Yodh, “Carbon Nanotube Aerogels,” Advanced Materials 19, 661-664 (2007).
- O.N. Torrens, D.E. Milkie, M. Zheng, J.M. Kikkawa, “Photoluminescence from Intertube Carrier Migration in Single-Walled Carbon Nanotube Bundles,” Nano Letters 6, 2864-2867 (2006).
- M.F. Islam, D.E. Milkie, O.N. Torrens, A.G. Yodh, J.M. Kikkawa, “Magnetic heterogeneity in single-wall carbon nanotubes,” Phys. Rev. B Rapid Communications 71, 201401 (2005).
- D.E. Milkie, C. Staii, S. Paulson, E. Hindman, A.T. Johnson, J.M. Kikkawa, “Controlled switching of optical emission energies in semiconducting single-walled carbon nanotubes,” Nano Letters 5, 1135-1138 (2005).
- S.A. McGill, R.I. Miller, O.N. Torrens, A. Mamchik, I-Wei Chen and J.M. Kikkawa, “Optical evidence for transient photo-induced magnetization in La0.7Ca0.3MnO3,” Phys. Rev. B 71, 075117 (2005).
- J. Vavro, J.M. Kikkawa, J.E. Fischer, “Metal-insulator transition in doped single wall carbon nanotubes,” Phys. Rev. B 71, 155410 (2005).
- M.B. Bryning, M.F. Islam, J.M. Kikkawa and A.G. Yodh, “Very low conductivity threshold in bulk isotropic single wall carbon nanotube epoxy composites,” Adv. Materials 17, 1186-1191 (2005).
- S.A. McGill, R.I. Miller, O.N. Torrens, A. Mamchik, I-Wei Chen and J.M. Kikkawa, “Dynamic Kerr effect and spectral weight transfer of the manganites,” Phys. Rev. Lett. 93, 47402-47405 (2004).
- M.F. Islam, D.E. Milkie, C.L. Kane, A.G. Yodh, J.M. Kikkawa, “Direct measurement of the polarized optical absorption cross-section of single-wall carbon nanotubes,” Phys. Rev. Lett. 93, p. 37404-37407 (2004).
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