Gerald Woods, Research Assistant Professor

General Physics Lab Director

Ph.D., physics, 2001, University of Tennessee

office:                     PHY006                 (813) 974-7351

e-mail:                   gwoods@cas.usf.edu

research interests: solid state & materials physics

·          magnetic materials

·          thin-films

·          spin-polarized tunneling

·          superconductivity

research outline:

Currently we are interested in spin-dependent transport in metallic ferromagnetic oxides. We have successfully investigated polycrystalline SrRu_1-x(Ti, Mn, Ni)_xO₃, as well as the CMR materials La_0.6(Sr, Ba)_0.4MnO₃, using point contact Andreev reflection (PCAR). This technique measures the conductance at a ferromagnetic/superconductor (F/S) junction, which has a contact size of typically ~ 1m. The conductance at zero-bias voltage illustrates that due to the spin imbalance at the Fermi level in a ferromagnet, suppression of Andreev reflection occurs. Our investigations will extend to studying the Andreev reflection process for F/S junctions in the presence of applied magnetic fields.

selected publications:

1. G. T. Woods, R. J. Soulen, Jr., I. I. Mazin, B Nadgorny, M. S. Osofsky, J. Sanders, H. Srikanth, and W. H. Egelhoff, “ Analysis of Point Contact Andreev Reflection Spectra in Spin Polarization Measurements”,     Phys. Rev. B 70, 54416 (2004).

2. G. T. Woods, P. Poddar, H. Srikanth, and Y. Mukovskii, “Observation of charge ordering and the ferromagnetic phase transition in single crystal LSMO using RF transverse susceptibility”, (Accepted for publication to Journal of Applied Physics).

3. J. Sanders, G. T. Woods, P. Poddar, H. Srikanth, B. Dabrowski, and S. Kolesnik, “Spin polarization measurements of polycrystalline ruthenates using point contact Andreev reflection”, (Accepted for publication to Journal of Applied Physics).

4. P. Poddar, G. T. Woods, S. Srinath and H. Srikanth, “Probing magnetic anisotropy and spin polarization in spintronic materials”, IEEE transactions in Nanotechnology, 4, issue 1 pp.59 (2005).

5. S. Cheng, G. T. Woods, K. Bussmann and R. J. Soulen, “Growth and

 magneto-transport properties of single crystal Fe_1-xCo_xS₂ (0.35<x<1)”, Journal. of Applied Physics, 93, 6847 (2003).

6. B. Nadgorny, M. Osofsky, D. J. Singh, G. T. Woods, R. J. Soulen,

 M. K. Lee, S. D. Bu and C. B. Eom, “ Measurement of spin polarization of epitaxial SrRuO₃ thin films”, Applied Phys. Lett. 82 427 (2003).

7. R. J. Soulen, M. Osofsky, J. H. Claassen. G. Trotter, G. T. Woods, Y. Ovchinnikov, V. Kreis and N. Trashawala, “ Characterization of the interface between a normal metal and a superconductor using magnetic screening”, IEEE Transactions on Applied Superconductivity, Volume 13, Issue 2, Part 3, 2003, Pages 2838-2841.

8. G.T. Woods G. P. Zhang, T. Callcott, L. Lin, G. S. Chang, B. Sales, D. Mandrus and J. He,“ Site-selected O 2p densities of states in NaV₂O₅ determined from angular-dependent x-ray absorption and emission spectra”, Phys Rev. B 65, 165108 (2002). 

9. G. P. Zhang, T. A. Callcott, G. T. Woods, L. Lin, Brian Sales, D. Mandrus and H.Je, “Electron correlation effects in Resonant Inelastic X-ray Scattering of NaV₂O₅”, Phys. Rev. Lett. 88 077401 (2002).

10. T. A. Callcott, L. Lin, G. T. Woods, G. P. Zhang, J. R. Thompson, and D. Ederer, “ Soft x-ray spectroscopy measurements of the p-like density of states of B in MgB₂ and evidence of surface boron oxides on exposed surfaces”, Phys. Rev. B 64 132504 (2001).

11. L. Lin, G. T. Woods, T. A. Callcott, “ Soft x-ray fluorescence spectra of III-V phosphides BP, GaP and InP” Phys Rev. B 63, 235107 (2001).

12. G. S. Chang, T. A. Callcott, G. P. Zhang, G. T. Woods, S. H. Kim,

 S. W. Shin, K. Jeong, C. N. Whang, and A. Moewes, “ Angular rotation of magnetic hysteresis of ion-irradiated ferromagnetic thin-films”, Applied Phys. Lett. 81, 3016 (2002).

13. G. P. Zhang, G. T. Woods, E. L. Shirley, T. A. Callcott, L. Lin, G. S. Chang, B. C. Sales, D. Mandrus, and He. J, “Orbital-resolved soft x-ray spectroscopy in NaV2O5”, Phys. Rev. B 65, 165107 (2002).

14. E. Z. Kurmaev, A. Moewes, G. T. Woods, T. A. Callcott, N. D. Zhigadlo, E. Takayama, V. R. Galakhov, and D. Ederer, “X-ray emission spectra of vanadium atoms in a new series of (Cu-V)-based high T_C superconductors”, Journal of Solid State Chemistry 170, 188 (2003).