We conduct a multi disciplinary and multi institutional research effort develop fundamental experimental and theoretical research into the physical properties of amorphous, ordered, and nanostructured solids. Materials being investigated include metals, insulators, semiconductors and amorphous solids. The Phenomena of interest include phase transitions, localization, electronic, magnetic, and lattice structure of solids. In particular emphasis is given to high temperature superconductors, heavy fermion systems and Kondo insulators. The research effort will focus on:
Synthesis, characterization, and analysis of new materials by novel methods and establishing the optimum processing parameters to produce high quality single crystal and bulk materials,
Thermal characterization under low or ultra-low temperatures, ultra-high pressures, and high magnetic fields.. The current active research areas include
The central focus will be understanding the basic mechanism of high temperature superconductivity in cuprates. Some of the research areas include, interaction between superconductivity and magnetism, improvement of the critical current density, theoretical and experimental investigation of the static and dynamic behavior of magnetic flux lines and pinning mechanisms, and identification of the superconducting order parameters. These topics are investigated under a variety of materials configurations such as thin and thick films, single crystals, melt processed and magnetically aligned specimens. In addition ternary silver alloys for cladding of high -Tc powders and deposition of thick films on polycrystalline metallic substrates will be investigated.
D and F-electron systems
RESEARCH ON THE ACTINIDES AND RELATED MATERIALS IN EXTREME CONDITIONS
The Fermi liquid (FL) theory of Landau has been very successful in describing the low temperature properties of metals. This description is summarized by the well-known expressions for the specific heat c(T) = _T, the magnetic susceptibility _(T) = const, and the electrical resistivity _(T) = _0 + AT2. A number materials classified as heavy fermion systems has been found not obey the standard FL behavior, at experimentally accessible temperatures. Detailed studies of such systems have led to the recognition that the FL framework may break down under specific conditions. This so-called non-Fermi liquid (NFL) state may be considered as a new type of ground state. In NFL materials, _(T)/T and c(T) diverge as T approaches 0 K, while _(T) follows a non quadratic temperature dependence.
Study of 5f electron system in actinide compounds and related Ce based compounds exhibit properties such as ferromagnetic superconductivity and high-Tc heavy fermion superconductivity
For many years it has been recognized that the understanding of the competition between the local spin fluctuations and the spin intersite coupling in heavy fermion systems is a key question of understanding the magnetic properties of these systems. In this project we will use the high field (up to 60T) and low temperature capabilities at the National High Magnetic Field Laboratory, Los Alamos Facility to investigate the effect of this competition in a few selected compounds. We will investigate the effect of high-magnetic field in the magnetovolume (thermal expansion and magnetostriction) and magnetotransport (Hall resistance and magnetoresistance) in a few Yb-based and Ce based compounds, in magnetic fields up to 20T and temperatures down to 20 mK. These measurements will be mostly carried out using the 20T superconducting magnet. Based on these results, the magnetotransport measurements can be extended to magnetic fields to 50T and temperatures down to 400 mK.
The research will also be extended to Rare Earth Hexaborides. This part of the project will be directed at establishing the relevant materials and material processing parameters to produce high quality single crystals of rare earth hexa-borides (RB6). Narrow-gap materials. The discovery of materials having a small semiconducting-like gap (a few meV), such as Ce3Bi4Pt3, SmB6, and FeSi, questions have been raised related to the nature of the gap. Analogous to a Kondo-Lattice material, we suggest that these compounds also may have a modestly large response to magnetic fields, specially as the magnetic field becomes comparable to the gap. In this part of the proposal we will probe the ground state properties of these materials by using magnetoresistance and magnetization measurements in magnetic fields up to 50T and temperatures down to 400mK.
National High Magnetic Field Laboratory and Los Alamos National Laboratory
State-of-the art facilitates exist within NHMFL to conduct a broad based investigation of superconducting oxide materials, heavy fermions and other exotic materials. At the NHMFL, we have the capability to reach magneticfields as high as 60T. Magnetotransport (magnetization, and Hall resistance) measurements can be performed in temperatures down to 20mK and 400mK using a 20T (superconducting) and 50T magnets, respectively. Magnetization, thermal-expansion, magnetostriction and heat capacity can also be measured in the 20T magnet in a wide temperature range. NHMFL has capabilities to perform magnetization measurements using a Quantum Design PPMS magnetometer, resistivity, Hall effect and heat capacity, as well as a variety of optical probes, such as Raman back scattering spectroscopy and an Ion Beam Facility. State-of the art facilities for bulk and single crystal sample preparation are available. Other additional measurement facilities are x-ray diffraction, electron microscope, thermal gravimetric analysis and differential thermal calorimetry.
How to apply
We are looking for dedicated students who are currently enrolled and/or plan to enroll in graduate programs in physics and engineering. Senior undergraduates majoring in physics, and engineering will be considered.
Eligible candidate must have a strong background in his or her respective field and adequate physics knowledge and must show strong interest in physics of materials, nanotechnology..
How To Apply:
Please send a letter of interest, curriculum vitae, original transcripts, and three letters of references. Candidates must be officially admitted to NC A&T State University before they begin their research. New graduate applicants must follow the graduate application process. For further information please follow http://www.ncat.edu. For additional information, please contact.
Dr. Abebe Kebede, Director , Condensed Matter Physics
Department of Physics
North Carolina A&T State University
Greensboro, NC 2741