Titles and Abstracts

January 28, 2013

Candidate for Assistant Professor in Condensed Matter

Measuring Magnetic Particles: Why it’s interesting and how to do it
Magnetic particles exist in many sizes and shapes. These particles can be found both in the natural world and in industrial systems. This talk presents an overview of these particles, where they are found, what their properties are and why measuring or looking for them is interesting. I will focus on my new technique for locating and measuring them called magnetic particle force microscopy (MPFM). MPFM is an atomic force microscope (AFM) based technique that has the unique ability to locate the particles in 3D and quantitatively measure their hysteresis curves. This is accomplished in a manner that is suitable for application to several natural and biological systems. Since MPFM is based off AFM it is uses a robust and simple, low cost setup which can be easily scaled upwards and downwards in sensitivity/particle size. An MPFM setup can also serve as a prototype for future microelectromechanical systems (MEMS) based detectors. These MEMS based magnetic particle detectors offer the ability to create commercial low cost systems that will simplify the instrument immensely.

January 30, 2013

Candidate for Assistant Professor in Condensed Matter

Exotic superconductivity revealed by heat capacity
The interplay between magnetism and superconductivity has been a central theme in condensed matter physics for the past 100 years. With the recent discovery of superconductivity in different classes of iron-based materials, interesting questions are posed regarding the mechanism of the superconducting state, which is intimately linked to the structure of the superconducting gap. Heat capacity is an excellent probe of the anomalous properties of conventional and unconventional superconductors. Because it directly probes the amount of quasiparticles determined by the gap topology, it is an excellent measure of the structure of the gap itself. During the talk I cover a brief overview of superconductivity focusing on the newly discovered iron-based materials, phase diagrams, pairing symmetry and experimental techniques. I show how detailed measurements of the specific heat at low temperatures and high magnetic fields together with the effect of controlled disorder provide access to the gap structure and pairing mechanism in conventional and unconventional superconductors. I discuss these issues in context of our extensive studies on multiband superconductivity in BaFe2-xCoxAs2 and give perspectives on these topics with extension to other exotic superconductors such as cuprates and heavy fermions.

February 4, 2013

Candidate for Assistant Professor in Condensed Matter

Novel Magnetic Materials for Energy Efficient Technologies
Magnetic materials play a crucial role in today’s technology. It is almost impossible to total up the enormity of applications whose functionality is strictly dependent on magnetic properties of materials. The applicability of such materials depends on how much control one has over their structure, properties and synthesis. In addition, the current global energy crisis demands the development of materials that can be used as alternative energy sources. Recent researches have shown that magnetic materials are potential candidates for use in technologies that canrevolutionize the efficiency of energy use. In this talk two such technologies that utilize magnetic materials will be discussed. The first part of the talk will discuss the concept of magnetocaloric effects (MCE), which is utilized in solid state cooling technology. This technology uses magnetic materials as coolant instead of the environmental unfriendly and energy inefficient compressed gas. The experimental techniques utilized to measure the magnetocaloric properties of a material will be discussed. Several materials that are potential candidates for use in this technology will also be discussed. Special attention will be paid to the magnetic phase transitions and associated magnetocaloric effects in Mn based Heusler alloys. The second part of the seminar will talk about permanent magnets and their applications in current technologies. An overview of the magnetic properties that determine the applicability of a material as permanent magnet will be given.

February 6, 2013

Candidate for Assistant Professor in Condensed Matter

Nanomagetization dynamics
Nanomagnetism is the study of magnetic order and phenomena at length scales ~100 nm and below.  While it is possible to fabricate nanoscale structures that comprise only a few atoms, it is also possible to observe nanoscale phenomena in much larger structures, such as micron scale ferromagnetic disks.  Due to competition between exchange energy and magnetic dipole energy, micron and sub-micron ferromagnetic disks can favor a magnetic vortex configuration as their ground state.  In this state, the magnetic ordering resembles a tiny tornado, with an eye, or a core, at the center, having dimensions ~ 10 nm.  We demonstrate the ability to control the position of this nanoscale core with high precision and repeatability, and to use its dynamic behavior as a probe of local structure.  In essence, we demonstrate the use of the vortex core as a nanoscale scanning probe of material defects in the thin film from which the magnetic disks are fabricated.  By modeling the interaction between the vortex core and various defect states, we seek to extract quantitative information regarding nanoscale material structure within the magnetic thin film.
 

February 13, 2013

Michael J. Pechan, Miami University Physics Department

Magnetodynamics and magnetostatics in nano-scale structures and spintronic materials
Following a introduction / tutorial on basic concepts in magnetic materials, I will discuss our recent and ongoing investigations in nanoscale physics and spintronics, where the main probe utilized in the research is ferromagnetic resonance. First I will present anisotropy and damping results in single crystal films of Fe3O4 on MgO with and without a silver overlayer (to probe spin-pumping effects) from room temperature through the Verwey transition. This project is done in collaboration with Casey Miller at U of South Florida. Next I will present recent results on tuning perpendicular magnetic anisotropy in CoPd/Fe/CoPd multilayers done in collaboration with Eric Fullerton at UC – San Diego.

February 20, 2013

Noureddine Melikechi, Delaware State University

Detection and classification of disease biomarkers in complex media using laser induced breakdown spectroscopy: the case of epithelial ovarian cancer
Epithelial ovarian cancer (EOC) is a disease that affects thousands of women and is the number one cause of deaths among gynecological cancers. Unfortunately, EOC does not present with obvious or specific symptoms which frequently results in diagnosis when the disease is at an advanced stage. Thus, the 5-year survival rate for women diagnosed with advanced EOC is approximately 40%. However, this rate increases to 95% if and when EOC is diagnosed at an early stage. This enhancement in survival rate demonstrates that it is crucial that researchers focus their efforts on the early detection of EOC. In this  presentation, I will discuss our progress towards achieving our aim: the development of  optical techniques for minimally invasive early detection of EOC using laser induced breakdown spectroscopy. I will show that using LIBS, it is possible to recognize numerous analyte proteins of interest to EOC in parallel. This is in part due to the relatively narrow and unique series of atomic emission lines of the micro- and nano-spheres.

March 20, 2013

Joseph W. Haus, University of Dayton
Optical Fibers for Lasers and Sensing Applications
Specialty optical fibers have been proposed for a diverse set of applications. In this talk I give a brief review of novel fiber geometries and discuss topics that we have explored including Talbot imaging in fibers with applications to high power lasers, a fiber laser whose produces cylindrical polarization states and biconical tapered fibers for sensing.

March 27, 2013

Mike Chapman, Georgia Institute of Technology

Non-equilibrium dynamics of a quantum pendulum
An inverted pendulum at rest is a prototype of unstable equilibrium and corresponds to a hyperbolic fixed point in the dynamical phase space. While mechanical pendulums operating at the quantum limit are currently unavailable in the lab, it is possible to study ultracold atomic many-body systems that have similar dynamical behavior.  In this talk, I will describe our recent measurements of the non-equilibrium dynamics of a spin-1 Bose-Einstein condensate ‘pendulum’ initialized to the hyperbolic fixed point of the phase space by quenching the system. Subsequent evolution of the quantum fluctuations lead to spin squeezing and non-Gaussian probability distributions that are in good agreement with exact quantum calculations. Additionally, we have demonstrated stabilization of the non-equilibrium dynamics by periodic application of phase shifts to the collective states of the system. These experiments demonstrate new methods of manipulating out-of-equilibrium quantum many-body systems, drawing together ideas from classical Hamiltonian dynamics and quantum squeezing of collective states.

April 3, 2013

Brett DePaolo, Kansas State University

Ionization in Direct Frequency Spectroscopy
Laser frequency combs are the hottest new tool in metrology. Recognized with a Nobel Prize in 2005 for its invention, Jan Hall and Theo Hänsch demonstrated the seemingly contradictory properties of broad bandwidth and ultra-high resolution that combs possess. In this seminar frequency combs their potential will be introduced. The focus will then be on one specialized use of combs: ionization. Both theory and experiment will be discussed.

April 10, 2013

Arthur Smith, Ohio University

Spin-polarized Scanning Tunneling Microscopy Investigations of Nitride-related Nanospintronic Systems
There are many interesting and unanswered questions within nitride-related magnetic/spintronic material systems which are ideally investigated using a combination approach consisting of UHV scanning tunneling microscopy and molecular beam epitaxy (MBE/STM).  Adding spin functionality to the STM tip, we are able to study spin structures via spin-polarized STM down to atomic scales for various systems including magnetic transition metal/semiconductor systems.  I will illustrate the power of our approach via our recent work on magnetic nitride spin pyramids, discuss new developments within my labs, and show where we are going next with our research.
 

April 17, 2013

Benson Memorial Lecture - Public Lecture

Eric Cornell, Nobel Laureate

JILA, NIST, University of Colorado Boulder

How symmetric is the electron? Looking for out-of-roundness at 10^-15 femtometers
The electron's electric dipole moment (eEDM) will be sensitive to particle physics beyond the standard model.  We make use of the extreme electric fields found within a molecular bond to pursue an experiment to set a new limit on eEDM at a level that should severely constrain supersymmetric models.

April 24, 2013

Ratna Naik, Professor of Physics
Department of Physics and Astronomy
Wayne State University

Vaman M. Naik, Professor of Physics
Department of Natural Sciences
University of Michigan-Dearborn

Cancer Detection in Pediatric Tumors and Head and Neck squamous cell carcinoma using Raman Spectroscopy
Recently, Raman spectroscopy has been used in the detection of a variety different cancers and other tissue abnormalities. It is a promising technique for real-time diagnosis. Raman spectroscopy is capable of providing highly detailed chemical information about a tissue sample and its noninvasive nature makes it an attractive tool for in vivo applications in medicine. We have investigated the archived tissues of head and neck squamous cell carcinoma and frozen pediatric tumors (neuroblastoma and ganglioneuroma). The effects of preserving the tissues on their Raman spectra and their utility in diagnosing the disease state of the tissues is investigated. The study shows that Raman spectroscopy in conjunction with multivariate statistical methods such as principal component analysis and discriminant function analysis can identify the disease state of the tissues that is consistent with the histopathological diagnosis.

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