Over the last few years, my group has focused on the study of electronic systems in confined geometries. Two-dimensional confinement is achieved when the electrons reside in a thin low bandgap semiconductor sandwiched between layers of a higher bandgap material. Further confinement results from processing the semiconductor sample into wires or dots using optical and electron-beam lithography techniques. As of late, it is in these reduced dimensional systems that some of the more significant developments in condensed matter physics have been found such as the integer and fractional quantum Hall effect, and quantized conductance in point contacts, to name a few.
At the University of Oklahoma, we have access to a particularly interesting semiconductor system, InSb. This material has an extremely low electron effective mass resulting in high mobility and a very large Lande g factor resulting in large spin effects. My group has been engaged in the study spin-orbit and spin transport in this system.
We perform our experiments at low temperatures (from 10K to 0.01K) and in high magnetic fields (up to 15 Tesla). In addition to our low temperature/high field facilities, we also use the optical lithography and electron-beam lithography facilities of the Solid State group. In this facility we can fabricate devices with tens of nanometer-sized features, package them for our experiments and perform room temperature inspection and characterization. In addition our affiliation with the OU/Arkansas Materials Center gives us access to a number of other magnetic, optical and electronic probes.
Representative Publications:
- D. Guzun, E.A. DeCuir, Jr., Vas. P. Kunets, Yu I. Mazur, G. Salamo, S.Q. Murphy, P.A.R. Dilhani Jayathilaka, T.D. Mishima, M.B. Santos, "Comprehensive doping and temperature studies of spin relaxation in InSb," Appl. Phys. Lett. 95, 241903 (2009).
- A. R. Dedigama, S. H. Gunawardana, S. Q. Murphy, M. Edirisooriya, N. Goel, T. D. Mishima and M. B. Santos, "Measurement of the Dresselhaus and Rashba Spin-orbit coupling via weak anti-localization in InSb quantum wells," in Narrow Gap Semiconductors 2007, Proceedings of the 13th International Converence, U. K. Book Series, Springer Proceedings in Physics, v.119, (2008).
- A. R. Dedigama, D. Deen, S. Q. Murphy, N. Goel, J. Keay, M. B. Santos, K. Suzuki, S. Miyashita, and Y. Hirayama, "Current focussing in InSb heterostructures," Physica E34 647 (2006).