In the nanoscience era, the properties of many exciting materials and devices will depend on the details of their composition down to the level of single atoms. Thus, the characterization of the structure and electronic properties of matter at the atomic scale is becoming ever more vital for economic and technological as well as for scientific reasons. The combination of atomic resolution Z-contrast scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) represents a powerful method to link the atomic and electronic structure to macroscopic properties, allowing materials, nanoscale systems and interfaces to be probed in unprecedented detail. Recent developments in correcting the aberrations of the lenses in the electron microscope have pushed the achievable spatial resolution and the sensitivity for imaging and spectroscopy into the sub-Å regime, providing a new level of insight into the structure, chemistry and physics of materials. The STEM group at Oak Ridge National Laboratory provides the ideal environment for this research due to its cutting edge instrumentation, including the microscope that currently holds the world record spatial resolution (see http://stem.ornl.gov for more details). Furthermore, ORNL is soon to become the host to the next generation of aberration-corrected microscopes. These machines will be able to provide electron probes with diameters below 0.5 Å, smaller than the size of many atomic orbitals, allowing us to take materials characterization to the next level of complexity.
We are looking for one or more graduate students willing to apply the STEM-EELS techniques readily available at ORNL and complementary theory to the study of complex oxide thin films and interfaces. Complex oxides present the most disparate behaviors (high Tc superconductivity, colossal magnetoresistance, ferroelectricity, etc.) and the low dimensionality in films and superlattices together with the presence of defects and interfaces may cause new physical phenomena to arise. The project would involve the characterization of such systems at the atomic scale, looking for phenomena such as interface charge transfer or localization, charge and/or orbital ordering, electronic phase separation, etc. Interested? Contact Prof. Ward Plummer (eplummer@utk.edu) or Dr. Maria Varela (mvarela@ornl.gov).
1. Development of
new materials using various material synthesis methods;
2. Discovery and investigation of novel phenomena via electrical, magnetic,
and thermal properties measurements (electrical resistivity, electrical tunneling,
thermal conductivity, thermoelectric power, magnetic susceptibility);
3. Study of quantum critical phenomena by measuring the electrical and thermal
transport properties tuned by material compositions, magnetic field (and pressure
that is under development);
4. Investigation of quantum effects in nanomaterials via electrical and thermal
transport properties measurements down to 0.3 K.
The
research of the low-energy nuclear theory group at UT concerns the study of
nuclei and nuclear astrophysics, which addresses the origin of the elements,
the structure and limits of nuclei, and the evolution of the cosmos. The main
questions for this field are: What
binds protons and neutrons into stable nuclei and rare isotopes? What is the
origin of simple patterns in complex nuclei? When and how did the elements from
iron to uranium originate? What causes stars to explode? The new and exciting frontier in nuclear
theory lies in the description of rare and short-lived nuclei. These nuclei
have unusual ratios of neutrons to protons. In this unique situation, important
inter-nucleon interactions are isolated and amplified. The weak binding of neutron-to-proton
asymmetric systems add additional flavor to the nuclear many-body problem. Exciting
new properties are, e.g. neutron halos, proton radioactivity, and changes in
shell structure.
The
UT/ORNL nuclear theory group consists of Drs. D. J. Dean, W. Nazarewicz, T. Papenbrock,
several long- and short-term visitors, postdoctoral associates, and students.
We investigate many aspects of the nuclear many-body problem with particular
emphasis on rare isotopes. We employ microscopic methods (involving density
functional theory, coupled cluster theory, Monte Carlo simulation, and shell
model diagonalizations), and tackle theoretical challenges
with pencil and paper, PCs, and the world’s most powerful supercomputers. We
also apply our ideas to other many-body problems, e.g., to ultracold atom gases. For more details, please see the titles
of our recent publications,
and come to our seminar.
The group has several international visitors each year, and collaborates with
experimental nuclear physicists at UT and ORNL. Three potential projects are
described below.
Contact:
Dr. David J. Dean at deandj@ornl.gov
Nuclear fission is one of
the best examples of nuclear large-amplitude collective motion. It is also a
complicated many-body proces which is difficult to
treat on the microscopic level. Various nuclear structure models have been applied
to fission barriers, lifetimes, and mass/charge distributions, and they provided
good overall description of the phenomenon and, in many cases, detailed predictions.
On the other hand, it is also true that the microscopic description of fission,
based on effective nucleon-nucleon interactions, still does not exist. The aim
of this project is to attack the problem of spontaneous fission using modern
theoretical methods and computational tools. This project is supported by the
grant from the National Nuclear Security Administration.
Contact:
Dr. Witold
Nazarewicz at witek@utk.edu
Microscopic nuclear structure
calculations with realistic effective interactions now provide a much-improved
and predictive description of light and medium mass nuclei. Based on the shell
model and new ideas concerning the most important correlations in nuclei, we
are extending this work to heavier nuclei and nuclei away from the valley of
stability. The prospective student will develop and implement efficient basis
state selection methods and perform structure calculations for medium to heavy
mass nuclei.
Contact:
Dr. Thomas Papenbrock
at papenbro@phy.ornl.gov
One of the most active areas of research in physics is Condensed Matter. A variety of investigations in recent years have unveiled interesting complex phenomena in several materials, that challenge our understanding of solids and may also lead to technological applications. Prominent among these developments are the areas of (1) High Temperature Superconductors, with critical temperatures that have reached over 150 K and with exotic pairing properties, (2) Colossal Magnetoresistance Manganites, with changes in DC current of many orders of magnitude upon the application of small magnetic fields, and (3) Nanosystems, where quantum effects play a key role. Some members of the Condensed Matter Theory group carry out investigations in these fields and several related ones. The main tools to analyze models for these materials involve computational techniques, since typically there are no small parameters to guide a perturbative expansion, but analytical calculations are also performed. The broad area of investigations outlined in this paragraph is usually referred to as Strongly Correlated Electrons. This field of investigations is also much related with the popular area called Complexity, due to recently unveiled similarities between soft and hard materials.
The UT/Physics Department group working in this research context has a high international visibility, and publishes in prestigious journals such as Physical Review Letters, Science, Physics World, and others. For a list of recent publications see http://correlate8.phys.utk.edu/group/. The group consists of two professors (Distinguished Professor E. Dagotto and Professor A. Moreo), and several students and postdocs. We receive the frequent visits of collaborators from the US and abroad.
A variety of clusters of PCs are available for the application of computational methods to the study of the materials described above. This includes clusters located at both UT and ORNL, and the combined number of PCs as of April 2005 is close to 300.
The group has a strong relation with the Theory Group of the Condensed Matter Sciences Division (CMSD) of Oak Ridge National Laboratory. This group and the entire CMSD will move soon to the Spallation Neutron Source (SNS), in a location right next to the ORNL Nanocenter, providing a superb environment for research in condensed matter. The "SNS hill'' of ORNL will become in a short time one of the most important research centers for condensed matter physics in the world.
Modern particle accelerators are tools to resolve smaller and smaller building blocks of matter and to understand the physics laws which hold them together. Today we are able to access a time in the evolution of our Universe of about 10^-10 seconds after the Big Bang corresponding to temperatures of 10^15 Kelvin. Fundamental questions can be addressed quantitatively, like: Why is our Universe full of things like us and stars and not empty? With the BaBar detector at the Linear Accelerator Center of the Stanford University (SLAC) we are able to measure differences in the behaviour of particles and anti-particles produced in collisions of electrons with anti-electrons. This probes our current understanding, the Standard Model of Particle Physics, or unexplored New Physics beyond it.
Graduate (and undergraduate) students perform analyses of such reactions, which show clean experimental signatures and contribute fundamentally to the understanding of the Universe. We provide guidance to study projects, which are highly recognized (e.g. Science Magazine Dec 2003 issue 'bottoms up). This allows the student to learn systematic approaches to complex problems and to be exposed to an international audience. Our group possesses a computer cluster with 80 high-performance CPUs and more than 2 TerraByte disk storage in support of the analyses. The cluster is also used in the development of a second generation World-Wide-Web, the GRID, which we support with software development and benchmark testing.
For future upgrades of BaBar or similar detector systems we investigate new design options for the Cherenkov detector DIRC. This is a novel technology applied for the first time in BaBar. Our R&D is detailed computer simulations of new designs and measurements of characteristics of new photon detectors. We are also part of the team, which supports and maintains the present running DIRC locally and at SLAC. As for computer technology High Energy Particle Physics is driving the development of cutting-edge technology, e.g. photon detectors which improve the efficiency of medical imaging devices reducing patient exposure to radiation.
Web Site: http://babar2.phys.utk.edu/~spanier/
The High Energy Theory group is currently working in the rapidly developing subject of black holes and other extended objects in string theory. Despite its shortcomings, string theory is still the only viable quantum theory of gravity. Recent results on black holes, D-branes, etc. are very exciting, having considerably advanced our understanding of quantum aspects of gravity such as thermodynamicalproperties of black holes (e.g., entropy), Hawking radiation and the information loss paradox. Their cosmological implications are also being investigated.
For more information, visit our Web site, or contact Dr. George Siopsis (e-mail: siopsis@tennessee.edu)
Web Site: http://aesop.phys.utk.eduThe Spallation Neutron Source (SNS), now under construction at Oak Ridge National Laboratory, will be the most powerful accelerator-based neutron scattering facility in the world. Because of SNS' unprecedented high beam intensity and other novel features (such as the world's first superconducting proton linac) there are several challenging accelerator physics research areas at SNS. In addition, the ongoing commissioning of the SNS accelerator complex offers tremendous research opportunities in:
Past graduate student theses:
S. Cousineau, Indiana University, Advisor Jeff Holmes: "Understanding Space Charge and Controlling Beam Loss in High Intensity Synchrotrons"
M. Doleans, University de Paris, Advisor Sang-ho Kim: "Studies of Elliptical Superconducting Cavities at Reduced Beta"
Present graduate student research projects:
Y. Sato, Indiana University, Advisor Jeff Holmes: Electron-Cloud Effects and the Electron-Proton Instability in the SNS Accumulator Ring
There are at present two openings for graduate student research in Accelerator Physics at the SNS. More information can be found at the following sites:
General project information: http://www.sns.gov/
Accelerator physics group: http://www.sns.gov//APGroup/APGroup.html
Contacts:
Stuart Henderson, iyu@ornl.gov
or telephone (865) 241-6794
Jeffrey Holmes, jzh@ornl.gov
or telephone (865)
576-5570
Norbert Holtkamp, nrp@ornl.gov or
telephone (865) 241-6945
Martin Stockli, qma@ornl.gov or telephone
(865) 241-8817
The title of our research is, "Structure and dynamics of complex
electronic oxides." We want to know how the arrangement and motion of atoms determine
the physical properties of solids. We use neutrons and x-rays from synchrotron
based national facilities, and study scattering. We use modeling and theory to
interpret the experimental findings. The materials we study include high-temperature
superconducting cuprates, superconducting cobaltates with water, colossal magneto-resistive
manganites, ferroelectric titanates, and other oxides.
We will add two-to-three graduate students in the next two years.
Takeshi Egami
Distinguished Scientist,Oak Ridge National Laboratory
Distinguished Professor, UT Departments of Materials Science/Physics and Astronomy
Dr. Thomas Thundat's research programs at the University of
Tennessee and the Oak Ridge National Laboratory focus on mechanical manifestations
of molecular and photonic interactions at interfaces and interphases. Understanding
the physics and chemistry involved in the nanomechanical effects of interaction
at interafces is important in designing and developing miniature sensors and devices
that exploit the nanoscale effects. For example at micro and nanoscale, delicate
forces such as surface tension, thermocapillarity, Marangoni, electrostatic and
van der Waals interactions play a significant role because of the large surface
to volume ratio in nanoscale systems.
However, our understanding of mechanics and function at the nanoscale is far from
complete. Recent progress in development of instrumentation that can measure displacements
and forces into the nanoscale and sub nanoscale regimes is paving the way for
a very exciting convergence of many traditionally separate fields and disciplines
ranging from molecular biology to fluid mechanics to quantum mechanics, and to
device physics and engineering. Present applied research programs include the
use of microcantilever sensors for the detection of chemical, biological, and
explosive material.
We can support one or two new graduate students full time.
Contacts:
Dr. Thomas Thundat at thundattg@ornl.gov
Dr. Lal Pinnaduwage at lpinnadu@utk.edu
Further information:
http://csep10.phys.utk.edu/guidry/StudentProjects_Guidry.html
Contact:
Dr. Mike Guidry at guidry@utk.edu
The research of the Relativistic Heavy Ion Physics (RHIP) group is focused on the study of nuclear matter at extreme temperatures and densities, which is a new and exciting field on the borderline between nuclear and high energy physics. At these extreme conditions of temperature and density nuclear matter will undergo a phase transition to a Quark-Gluon Plasma. In this new phase nuclear matter does not any more consist primarily of protons and neutrons, but instead of deconfined quarks and gluons. Experimentally we are creating high temperature nuclear matter by colliding heavy nuclei (heavy ions) at very high energies (ultrarelativistic energies) at nuclear accelerators. Another focus of our research is the spin structure of the proton. The measurement of the spin structure functions of proton can also be accomplish within the PHENIX experiment. In general the RHIP group has two-to-four students involved in our research at different stages in their graduate studies. We are always looking for new students, so please do not hesitate to check us out at: http://www.phys.utk.edu/rhip/ or contact us directly through the contact info at: http://www.phys.utk.edu/rhip/RHIP_People.htm.
Professor Hanno
Weitering has one, possibly two openings for studies of electrical conductivity
through atom wires. See: http://www.phys.utk.edu/cmp/cmp_research_surfacenanowires.htm.
Contact:
Dr. Hanno Weitering at hanno@utk.edu
Collective electronic quantum effects on the nanoscale are under investigation for the development of semsors and signal electronics, all-photonic amplification, thin-film displays, current modulation in conductors via photonics, photovoltaics, and other applications. Sensors are based upon novel systems that are micro-electro-mechanical systems (MEMS) or nanoscale systems. The associated electronics has an application-specific integrated circuit (ASIC) developed jointly with industry and providing radio transmission and signal processing in a self-contained system. Quantum tunneling in metal-oxide-metal junctions is being explored and junctions are fabricated using electron-beam lithography. Sensors now under development for the National Institutes of Health include implantable sensors for the detection of changes of biochemical compounds and physiological signals. All-photonic amplification and methods for induction of electronic current modulation in conductors are studied with surface plasmons, which are quanta of collective electronic effects at surfaces. Optical fiber sensors using nanoparticles of gold as a coating are researched for detection of a variety of environmental compounds. The group has also developed new forms of scanning-probe microscopy and spectroscopy using photon tunneling and the tunneling of surface plasmons. Other projects include a micro-optical spectrometer based upon surface plasmon filtering and the development of a molecular-beam technology for coating of sensors.
Current Graduate Students are Phil Evans and Philip Boudreaux of UT and Aude Lereu of the U of Dijon. Additional graduate students can join the group on a 25%-time RA that would evolve into a 50%-time RA or greater as their academic program progresses.
See movies of Dr. Ferrell's research: taking the pulse train in the infrared and transferring it to visible light (Movie One, Movie Two).
Contact:Dr. Thomas L. Ferrell at tferrell@utk.edu
Research scope: Measuring properties of nuclei far from stability. Exotic decy modes: proton and two proton radioactivity. Isomeric states in very neutron rich nuclei.
In the context of my research on nuclei far from stability carried out at radioactive beam facilities at Oak Ridge National Laboratory and National Superconducting Cycloton at MSU I will be initiating Digital Pulse Processing Laboratory at the University of Tennessee. The aim is to explore the potential of digital pulse shape processing techniques in measuring the rare types of radioactivities and train students in applying most advanced technologies in nuclear physics. See the Experimental Nuclear Structure homepage at http://www.phys.utk.edu/expnuclear/.
Contact:Dr. Robert Grzywacz at grzywacz@mail.phy.ornl.gov
When in 1930 Wolfgang Pauli invented neutrino particles for the explanation of beta-decay experiments he bet a case of champane that nobody ever will be able to detect these particles. Nowdays detection of neutrinos is a field of precision experimentation in Physics: we recently learned that neutrinos have masses and can be transformed from one type to another. Next questions to learn is whether CP-symmetry is violated in neutrino interactions and whetehr neutrinos are Majorana or Dirac particles. UT HEP group is involved in the KamLAND experiment where anti-neutrinos produced by the power nuclear reactors are detected in the large liquid scintillator detector deep underground in Japan. For the first time the disappearance of reactor anti-neutrinos (due to oscillations to the other neutrino types) was observed in KamLAND. We discuss in our group a possibility of measurement of theta_13 with reactor anti-neutrinos: the key parameter for the measurement of CP-violation in neutrino sector. We also have plans to participate in the new experiment MAJORANA that will attempt to shed the light on the nature of neutrino particles. Our group also lead an effort to perform in the future at the Spallation Neutron Source (ORNL) precision measurements of neutrino interactions with nuclei that will help to understand how the supernovae work.
Contacts: Dr. Yuri Efremenko (UT/ORNL) at efremenk@unix.utk.eduWeb Sites:
KamLAND
webpage
New Theta_13 Measurement
Majorana Project
Neutrinos at SNS webpage
Our group consists of a racemic mixture of physics and chemistry graduate students pursuing research on a wide variety of topics. One underlying theme of the research involves the study of singly- and multiply-charged negative ions. Included in this research is the characterization of dipole- and quadrupole-bound anions. These are very diffuse and weakly bound anions which could play a role in the transport of electrons through gases and along surfaces. Our group is also interested in the detection and characterization of anions in the atmosphere as well as their potential role in the complex physics and chemistry of the atmosphere.
High resolution electron beams and pulsed tunable lasers are employed to study the spectroscopic properties of gaseous molecules in nozzle-jet expansions or nano-materials produced by laser-matter interactions. A technique employing Raman Spectroscopy of samples under liquid nitrogen is used to examine the symmetric (Raman allowed) vibrational energy levels and a Bomem DA8 FTIR spectrometer is employed to record the asymmetric (IR active) vibrational modes. All of the experimental studies have a strong connection to theory.
Further information is available online at: http://web.utk.edu/~rcompton/link.html
Contact:Dr. Robert N. Compton at rcompton@utk.edu
We focus on the scientific challenges and opportunities associated with understanding the highly correlated electronic behavior exhibited in transition metal oxides (TMOs). TMOs have been at the forefront of condensed matter physics research since the discovery of high-transition-temperature (high-Tc) superconductivity nearly 15 years ago, and interest in these materials continues unabated because of the richness of their novel properties. The outstanding characteristic of these materials is the dominant role played by electron-electron, electron-lattice, and spin-lattice interactions. Reaching a satisfactory understanding of these "highly correlated electron systems" poses one of the most profound intellectual challenges in the physical sciences today. Our objective of this research program is to explore and understand the microscopic origins of various phases in the TMOs using neutron scattering as a primary tool. The program has two key components: advanced synthesis and neutron scattering. For synthesis, we will use infra-red floating zone furnace located at 320 SERF to grow the most interesting TMO single crystals. Neutron scattering is an indispensable tool for studying the highly correlated electron materials, and for this we will use the newly upgraded high-flux isotope reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) as well as other world-class facilities in US and Europe. The materials are "colossal" magnetoresistance (CMR) manganese oxides, high-Tc copper-oxide superconductors and other interesting oxide materials. The prospect for future job opportunities for graduate students is excellent for neutron scattering because of the construction of spallation neutron source (see http://www.sns.gov) and the upgrade at the high-flux isotope reactor (see http://neutrons.ornl.gov). We will have one or two openings for full RA support in the Fall of 2004, perspective students are encouraged to meet with Dr. Pengcheng Dai in 407A Nielsen.
Further information is available online at: http://www.phys.utk.edu/cmp/cmp_people_dai.htm
Contact:Dr. Pengcheng Dai at piq@ornl.gov
Laboratory Mission Statement: "To go boldly where no reductionists have gone before, bringing the distilled wisdom of the physicist to bear on problems far too complex for pure reductionists."
The research areas listed below cover many interest areas in the laboratory. At present we have no GRA support but would be pleased to discuss your interests with you. Not all the projects below are presently active but could be encouraged to come alive for the right student. Hyperspectral imaging studies in data processing and interpretation of hyperspectral data in the visible and infrared using cameras created by David Glenar, NASA/GSFC and John Hillman, NASA/GSFC (retired) and University of Maryland, Astronomy Department. These projects are open-ended and in progress or planned to commence in the near future. The projects include imaging the Star Spangled Banner in the National Museum of American History (Smithsonian), imaging of paintings for studies of origin and authentication, analysis of the SL-9 comet crash into Jupiter, and others.
Graduate Students: James Wicker, Ph.D. Candidate; John Meyer, M.S. Candidate; Forrest Hoffman, M.S. Candidate
Contact: Dr. Bill Blass, Director, at wblass@utk.edu