Condensed matter physics encompasses the study of solids, liquids and complex materials. Faculty at NIU are engaged in the study of phenomena relevant to magnetism, superconductivity, and ferroelectricity. Other work centers on how to synthesize new materials, or how to study the mechanical properties of novel materials. This research has relevance to a wide range of practical applications including helping design the next generation of computer memory, designing new types of refrigeration, creating fuel cells to power electric cars, and creating stronger polymers. The condensed matter group includes theorists and experimentalists. Experimental facilities at NIU include an electron microscope, two physical property measurement systems, a Mossbauer spectrometer, a powder x-ray diffractometer, and two surface x-ray diffractometers. The physics department is a member of NIU’s Institute for Nanoscience and Engineering Technology (INSET) and as such faculty and students have access to a class 100 clean room containing a wide array of fabrication and characterization instruments and deposition systems. Some faculty in the department also base their research programs at Argonne National Laboratory, located 44 miles southeast of the University. Argonne is home to several national user facilities including the Advanced Photon Source, the Electron Microscopy Center, and the Center for Nanomaterials.
Brown's group studies the condensed matter physics of magnetic systems using Mossbauer spectroscopy, nuclear resonant x-ray scattering, and x-ray crystallography as as function of temperature, magnetic field, and pressure. Areas of particular interest to Professor Brown are spintronics, magnetoresistance, magnetocaloric effects, phonon density of states, and magnetic and pressure-induced structural and electronic phase transitions.
Omar Chmaissem’s scientific background and research interests involve detailed and precise characterizations of the structures and properties of advanced functional oxides. Neutron powder diffraction and high resolution x-rays are the primary tools of interest that helped determine the exact oxygen stoichiometry and structures of a wide variety of exotic copper based superconductors, colossal Magnetoresistive manganites, magnetic ruthenates, and heavy fermions.
Additionally, over the past few years, Omar Chmaissem established a new laboratory for the controlled growth and synthesis of oxide-based thin films, multilayers, and nanoparticles using Laser-Assisted Molecular Beam Epitaxy (LMBE). Characterization of the films and artificial heterostructures is performed using a state-of-the art x-ray microdiffraction and advanced x-ray spectroscopies at the Advanced Photon Source of Argonne National Laboratory.
Dabrowski’s group research involves production and characterization of complex oxide materials and development of relationships between structural and physical properties. Current research focuses on mixed oxygen-ion and electronic conductors, colossal magneto-resistivity, highly spin-polarized ferromagnets, thermoelectrics, metal-insulator transitions, magnetic oxide semiconductors, and high temperature superconductors. Materials engineering on an atomic scale that uses detailed knowledge of the crystal chemistry, including interactions between bulk material, grain boundaries and local defects is employed for making the desired atomic arrangements and probing how the local environment influences properties of the new structures.
Ito's group studies relationship between structures and their properties of bulk and interfaces of nanostructures in atomic scale, using transmission electron microscopy and its related spectroscopy techniques electron energy-loss spectroscopy and x-ray emission spectroscopy. Recent interests are on nanoscale anisotropy found in spin-electronic materials and structures, superconducting nanowires and ribbons.]
Professor Emeritus in Materials Science
Lurio's group studies structural and dynamic properties of fluids and complex materials primarily using x-ray and light scattering. Recent work includes studies of the structure and dynamics of thin polymer films and biomembranes, studies of the properties of liquid helium in confined geometries, and measurements of critical phenomena in binary fluid mixtures.
Thompson's group studies surface, interface and bulk structures to understand the correlation between structure and physical properties. Current aspects of her research include studies in situ characterization using x-ray techniques at the Advanced Photon Source during processing of metal organic chemical vapor deposition (MOCVD) of nitrides and oxides. Her group also synthesizes and studies epitaxial thin films and surfaces, studying strain relaxation processes using real-time x-ray techniques and ex-situ atomic force microscopy, and the effect of surface and size on thin film properties at the nanoscale.
Van Veenendaal studies condensed-matter theory and in particular the interaction between x-rays and solids. The focus is on strongly correlated systems such as transition-metal and rare-earth compounds. The research involves, e.g. x-ray dichroism and inelastic x-ray scattering, magnetism, orbital and charge excitations. Methods include exact diagonalization of small clusters, many-body techniques, and analytical methods to study key features of spectroscopy.
The theoretical research in Winkler's group is centered around spin-dependent phenomena in solid state systems. Questions of interest include spin-orbit coupling, spin dynamics, and transport and optics in systems with reduced dimensionality. Numerical studies are complemented by simple and transparent analytical models that capture the important physics. Computer-algebra systems represent an important tool for this work.
Xiao's group currently works in the field of nanoscience, with emphasis on superconductivity in confined geometries. Various synthesis approaches have been developed or used to fabricate superconductors in the forms of nanowires, nanoribbons, shape-controlled nanocrystals, and antidot arrays (films containing arrays of nanoscale holes). Size and shape effect on superconductivity and magnetic flux pinning and dynamics have been the research focus. Potential applications of nanomaterials are also explored, with current interest on development of robust hydrogen gas sensors with short response times and high sensitivities.