Surface Physics Research
The experimentalists and theorists of the surface physics group are united by a desire to understand the properties of materials with reduced dimensionality, i.e., nanomaterials and systems with surfaces and interfaces. Five Physics faculty members work in this interdisciplinary area: Marija Gajdardziska, Carol Hirschmugl, Lian Li, Paul Lyman, and Michael Weinert. In addition, this group interacts fruitfully with colleagues in Chemistry, Materials, and Mechanical Engineering through the interdisciplinary Laboratory for Surface Studies.
Research centers on the production, characterization, and understanding of novel materials, nanostructures, surface reconstructions, and thin films. Current areas of research include III-V nitrides, polar oxide surfaces and interfaces, metallic surface alloys, graphene, wide-bandgap semiconductors, adsorption on oxide and metal surfaces, fundamentals of electron and x-ray scattering, and surface magnetism.
Experimental methods include film growth by molecular beam epitaxy (MBE) and atomic layer deposition (ALD), and surface and interface characterization using a host of analytical methods. Special techniques and/or facilities used include picoAmpere low-energy electron diffraction for LEED-IV studies of insulators, scanning tunneling microscopy (STM), surface x-ray diffraction (SXRD), high-resolution transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and x-ray magnetic circular dichroism (XMCD). National facilities, including synchrotrons at Argonne National Lab and Brookhaven National Lab, and TEM centers at Lawrence Berkeley National Lab and Oak Ridge National Lab, are strongly utilized. In addition, the standard techniques of low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and reflection high-energy electron diffraction (RHEED) are widely available in-house at UWM.
Theoretical areas of interest include phase stability of materials, direct methods for interpreting x-ray and electron scattering data, electronic and magnetic properties of novel materials, holographic LEED and LEED-IV surface analysis, and ab-initio surface atomic structure determination. Theoretical methods include multiple-scattering calculations for electrons in matter, first-principles calculations of total energies and electronic structure, and phase-recovery methods for x-ray and electron diffraction. Computing facilities include a several multi-node clusters for high-performance numerical calculations.