Experimental Condensed Matter Physics

Prof. W. P. Beyermann,   Prof. D. MacLaughlin,   Prof. A. Mills,   Prof. J. Shi ,   Prof. U. Mohideen,   Asst. Prof. R. Kawakami,   Asst. Prof. J. Lau,   Prof. H. W. K. Tom,   Prof. J. A. Yarmoff

Experimental condensed matter physics investigates the physical properties of ordinary matter around us in various forms: solids, liquids, engineered materials, and nanostructures. These systems have exhibited fascinating behavior which challenges our understanding of nature at a fundamental level. Physicists have invented many of the experimental tools used to probe the electronic, optical, magnetic, and vibrational properties of matter, and the development of increasingly sensitive measurement techniques continues on. Condensed matter physicists are also involved in the synthesis of artificially-structured materials, nanostructures, and nanoscale devices, which often manifest interesting behavior that is distinctly quantum mechanical in origin. Related emerging areas are Biophysics, which seeks to develop a physical basis of biological behavior, and Environmental Physics, which utilizes experimental techniques developed by physicists to address environmental concerns.

The Experimental Condensed Matter Physics Group at the UCR Department of Physics has active research programs in novel materials and nanostructures, highly-correlated electron physics, surface science, biophysics, precision measurement, linear and non-linear optics, muon-based spectroscopy, high-density positronium gases, spintronics, and molecular electronics.

Professor Ward Beyermann specializes in the transport and thermodynamic properties of highly correlated electronic condensed matter systems, semiconductors, and nanostructures. These include materials where the strong interactions between the electrons lead to unusual properties at low temperatures. Specific heat and resisitivity are measured down to millikelvin temperatures and in high magnetic fields. Some of the systems investigated include lanthanide and actinide intermetallic compounds, lanthanide intermetallic borocarbides, carbon-fullerene materials, DNA, magnetic nanowires, and ZnO heterostructures.

Professor Roland Kawakami's research focuses on nanoscale magnetism, spin-polarized electron transport, and spin dynamics in semiconductors. Of primary importance is the development of novel hybrid structures that integrate the various functionalities (i.e., photonic, electronic, magnetic) of dissimilar materials such as GaAs, Si, MgO, carbon nanotubes, organic semiconductors, and ferromagnets. Molecular beam epitaxy is the method of choice for the fabrication of these hybrid structures due to the high purity atom-by-atom (or molecule-by-molecule) deposition. Ultrafast optical techniques are utilized to measure the spin and magnetization dynamics in these structures, and low temperature magnetotransport measurements are utilized to identify the flow of spin-polarized electrons in nanoscale devices.

Professor Chun Ning “Jeanie” Lau’s research focuses on (1) the exploration of novel phenomena in low dimensional nano-structures that arise from quantum confinement of atoms and electrons, and (2) engineering novel electrical, electro-mechanical and optical devices based on these novel properties. For example, under investigation are the limit of superconductivity in ultra-thin nanowires, dynamics of electrons and phonons in single-walled carbon nanotubes, novel electronic properties of single-layer graphene, and use of organic molecules as nanoscale memory elements and logic gates.

Professor Doug MacLaughlin's research interests center on understanding the behavior of certain exotic metals, alloys, and superconductors, in which the unifying thread is the importance of strong correlations between the conducting electrons. The so-called "heavy fermion" f-electron compounds comprise one class of strongly correlated electron materials. Electrons in the well-known high temperature superconductors are also strongly correlated. Viable explanations for much of the behavior of these materials continue to be elusive. Our research uses magnetic resonance, principally nuclear magnetic resonance (NMR) and the related muon spin rotation (µSR) technique, as a local probe of magnetic phenomena. Both techniques sense static and dynamic magnetic behavior on the atomic scale, and yield important information on the effect of strong electron correlations.

Professor Allen Mills seeks to make the first Bose-Einstein condensed positronium annihilation gamma ray laser, and to make a DNA neural network computer ten thousand times bigger than a human brain. Prof. Mills has pioneered several techniques in the field of positron physics including the single crystal negative affinity positron moderator (1978,9), brightness enhancement of slow positron beams (1980) and the rare gas solid moderator (1986). He is currently working on applying these techniques to the problem of obtaining a Bose-Einstein condensed gas of positronium atoms. He has worked DNA computation since 1996. Most recently he was part of the team lead by Bernard Yurke of Bell Laboratories that developed a molecular-size machine made from DNA molecules that operates using DNA as a fuel. His interests also include the study of solid-state materials and devices.

Professor Umar Mohideen's main research focus has been on (1) exploring the nature of the quantum vacuum by pioneering fundamental force measurements such as the normal and lateral Casimir force using an Atomic Force Microscope and (2) studying single molecule and nanostructures in condensed matter by scanning microscopy techniques such as the Atomic Force Microscopy, Scanning Tunneling Microscopy and the Near Field Scanning Optical Microscopy. He has also performed collaborative research activities in the areas of Plasma Physics and Biophysics.

Professor Jing Shi is interested in spin-dependent transport and tunneling in solids. In particular, he is exploring spin injection, detection, and transport in inorganic and organic semiconductors as well as metals. He is also working on the magnetization reversal of nanoscale magnetic structures and devices.

Professor Harry Tom specializes in nonlinear optics and femtosecond time-resolved laser techniques and is particularly interested in surface dynamics, laser-induced surface chemical reactions, laser-induced phase transitions in bulk materials, nonlinear optics of the water/solid interface, terahertz spectroscopy, and most recently in magnetic nanostructures and spintronics. Tom is Co-Director of the Environmental Physics graduate program, an interdisciplinary program in which condensed matter physicists and environmental scientists collaborate in joint research and graduate training.

Professor Jory Yarmoff investigates the physical and chemical properties of solid surfaces, and the interaction of radiation with surfaces. Experimental studies in ultra-high vacuum provide an atomic-scale picture of surface geometric, electronic and chemical structures, chemical reactions that occur at surfaces, and the interaction of radiation with surfaces. These results have applications in diverse technological fields, such as semiconductor processing, catalytic chemistry, and environmental remediation. Current efforts include the use of neutralization during ion scattering as a measure of the electronic structure of adatoms, molecules and nanostructures, the investigation of high mobility organic single crystal semiconductor surfaces, and the interaction of radiation with oxide materials.