This experimental condensed matter physics project deals with nanofabrication techniques that will enable electronic devices that operate by means of physical mechanisms different from existing technology. By incorporating a single metal particle less than 10 nm in diameter into a tunneling device, it becomes possible to manipulate the flow of electrons via individual "electron-in-a-box" energy levels within the particle, and to measure the spectrum of these quantum-mechanical states. This research will study the processes which affect electron transport in this new regime-at the level of single energy levels-for magnetic, superconducting, and normal-metal particles. In addition, the ability to measure the spectrum of quantum levels in a nanoparticle will be used as a tool in investigations of other fundamental questions of nm-scale physics. Topics of primary interest include spin-polarized electron tunneling into single quantum states, the mechanisms of energy and spin relaxation between energy levels, the effects of electronic interactions on the level spectra, the mechanisms of magnetization reversal in nm-scale ferromagnetic particles, and the effects of impurities on quantized energy levels. The research provides exceptional opportunities for graduate students and research associates to be trained in frontier science areas that will prepare them for a range of careers in industry, academe, and government. %%% When a piece of metal is made less than about 10 nanometers in diameter, so that it contains about 10,000 atoms or less, electrons cannot flow through the metal particle with an arbitrary energy- they can flow only with only one of a restricted range of so-called quantized energies. This means that very small electrical devices are entering a new regime, where electrons can be manipulated to flow via individual energy states, in contrast to existing devices where the energy levels are effectively a continuum of states. This experimental condensed matter physics project is aimed at characterizing and understanding all the processes which affect electron flow in this new regime-at the level of single energy levels- for magnetic, superconducting, and normal-metal particles. In addition, the ability to measure the spectrum of electronic levels in a nano-particle will be used as a tool in investigations of other fundamental questions of nanometer-scale physics, such as the behavior of the electron's spin when an electron hops onto a small magnetic particle, the rate at which an electron may relax from a higher-energy to low-energy state within a particle, and the effects of impurities on the quantized levels. The research provides exceptional opportunities for graduate students and research associates to be trained in frontier science areas that will prepare them for a range of careers in industry, academe, and government. ***
