Professor John Gregg

Abstract:

We present a joint experimental and theoretical study on the transport properties of nickel nanoconstrictions. The samples show highly non-linear and asymmetric I-V characteristics when the conductance is smaller than G(0) = 2e(2)/h, and huge magneto resistance ratios exceeding 99.9%. We model a single point contact in a two-band tight-binding model as a 2 x 2 nickel chain connected to two semi-infinite nickel leads. The magnetoresistance is calculated by using a non-equilibrium Green's function technique. (C) 2003 Published by Elsevier B.V.

Abstract:

A novel high gain silicon based spin transistor was presented. The spin transistors were fabricated using standard photolithography on n- and p-type silicon-on-insulator (SOI) wafers. The results showed that connected in common emitter configuration and measured at room temperature, the transistor exhibited similar characteristics to that of a conventional bipolar transistor, except the current gain is negative.

Abstract:

This review is intended as an introduction to mesomagnetism, with an emphasis on what the defining length scales and their origins are. It includes a brief introduction to the mathematics of domains and domain walls before examining the domain patterns and their stability in 1D and 2D confined magnetic structures. This is followed by an investigation of the effects of size and temperature on confined magnetic structures. Then, the relationship between mesomagnetism and the developing field of spin electronics is discussed. In particular, the various types of magnetoresistance, with an emphasis on the theory and applications of giant magnetoresistance and tunneling magnetoresistance, are studied. Single electronics are briefly examined before concluding with an outlook on future developments in mesomagnetism.