Materials Science
Research Topics

In this section you will find links to more details of our research effort. Although we are primarily experimentalists, we also do modeling and a bit of theory to help explain our data. This is particularly important in helping to explain the photoelectron angular distributions that we find with our display analyzer.

Our underlying motivation is to understand the connections between the electronic and geometric structures of surfaces and films with magnetic and other properties.

Much of our work is conducted at the LSU CAMD synchrotron light source where we use several different beamlines for just about any photon-induced experiment that you can imagine. This includes the typical alphabet-soup of surface techniques such as UPS, XPS, ARPES, EXAFS, MCD, MLD(AD) etc.

As the dimension of a material is reduced, new properties emerge. We are interested in the electronic and geometric structures of wires with nanoscale dimensions.

We show that these nanowires have quasi 1-D electronic structures allowing us to probe exotic physics in reduced dimensions.

These wires exhibit unusual optical properties allowing applications in diverse areas such as optoelectronics and photochemistry.

Oxides containing magnetic elements can have unusual properties.

Half-metallic materials such as Fe₃O₄ have one spin type at the Fermi level and hold great promise in devices based on spin-dependent transport. Just as the control of the motion of electronic charge gave rise to todays electronics, control of the motion of electronic spins may spawn a totally new "spintronics."

We have focused on thin-films of this oxide grown on Cu substrates, for obvious device-related reasons. Remarkably, our STM studies show that one can grow large oriented crystallites of this material on materials of device relevance.

Surfaces differ from the bulk and alloys can form from bulk immiscible materials.

Normally Ni and Ag do not alloy but a surface changes free energies, and can permit intermixing.

Intermetallic alloys such as FeAl can be oxidized to create a thin Al₂O₃ layer for growing nanowires that are electrically decoupled from the substrate.

Using the WIEN2k implementation of density functional theory we have compared photoelectron angular distributions with predictions from first principles.

We have found that the angular distributions from the Fermi surface of fcc-Co are dominated by the structure of the final state and do not look like cross-sections of the Fermi surface.

This suggests that a strong coupling between theory and experiment will be particularly important in understanding ARPES from heavy fermions and HTSC's.

Layered materials exhibit fascinating physics such as LaSb₂ which shows a linear magnetoresistance despite being composed of non-magnetic elements.

The Fermi surface is highly nested and likely gives rise to density-wave excitations.

These kinds of excitations may play a role in the properties exhibited by other materials like HTSC's.

Oxides present fascinating opportunities for surface chemistry as well as exhibiting properties of fundamental importance such as metal-insulator transitions.