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Event Date Summary
Samo Kralj, University of Maribor, Impact of intrinsic and extrinsic curvature on membrane shapes Wed. November 29th, 2017
12:30 pm-1:30 pm

Prof. Samo Kralj

University of Maribor, Maribor & Jožef Stefan Institute, Ljubljana, Slovenia

 

 Impact of intrinsic and extrinsic curvature on membrane shapes

Red blood cells (erythrocytes) are present in almost all vertebrates and their main function is the transport of oxygen to the body tissues. Their shape dominantly influences their functionality. In almost all mammals in normal conditions erythrocytes adopt a disk-like (discocyte) shape which optimizes their flow properties in large vessels and capillaries. Experimentally measured values  of  the  relative volume v of stable discocyte shapes  range in a relatively broad window.

No seminar, Faculty meeting Mon. November 27th, 2017
12:45 pm-2:00 pm
Farida Selim, Bowling Green State University, Positron Annihilation Spectroscopy and Measurements of Origin of Novel Electronic Phenomena in Semiconductors and Oxides Mon. November 20th, 2017
12:45 pm-1:45 pm

Positron Annihilation Spectroscopy and Measurements of Origin of Novel Electronic Phenomena in Semiconductors and Oxides    

Farida A. Selim, Department of Physics and Astronomy, Bowling Green State University  

Center for Photochemical Sciences, Bowling Green State University

 Positron Annihilation Spectroscopy (PAS) has been established as an effective tool to probe electron states and measure atomic scale defects in solids. However, when combined with other techniques, PAS becomes also a powerful tool for revealing and explaining many interesting electronic phenomena. In our laboratory, we combined PAS with structural and transport measurements as well as with infrared,

Vincent Sokalski, Carnegie Mellon University, A New Kind of Magnetism – The Dzyaloshinskii-Moriya Interaction Mon. November 13th, 2017
12:45 pm-1:45 pm

A New Kind of Magnetism – The Dzyaloshinskii-Moriya Interaction

Vincent Sokalski, Dept. of Materials Science and Engineering, Carnegie Mellon University

Magnetism has had a profound effect on our everyday lives from compass needles in ancient times to the modern hard disc drive in today’s computers.  The existence of magnetic materials is rooted in the Heisenberg exchange interaction energy, , which favors parallel (or anti-parallel) alignment of neighboring spin vectors and their associated magnetic dipole moments as found, for example, in Fe, Ni, and Co.  In the past decade a different type of magnetic exchange came to the forefront of modern physics called the Dzyaloshinskii-Moriya Interaction (DMI) given by ,

Jeanie Lau, The Ohio State University, Spin, Charge and Heat Transport in Low-Dimensional Materials Mon. November 6th, 2017
12:45 pm-1:45 pm

Spin, Charge and Heat Transport in Low-Dimensional Materials

Chun Ning (Jeanie) Lau

Department of Physics, The Ohio State University, Columbus, OH 43210, USA

 

Low dimensional materials constitute an exciting and unusually tunable platform for investigation of both fundamental phenomena and electronic applications. Here I will present our results on transport measurements of high quality few-layer phosphorene devices, and the unprecedented current carrying capacity of carbon nanotube “hot dogs”. In the second half of the talk, I will present our recent observation of robust long distance spin transport through the antiferromagnetic state in graphene.

Eric Stinaff, Ohio University, Opto-electronic studies of novel self-contacted 2D materials based devices Mon. October 16th, 2017
12:45 pm-1:45 pm

Opto-electronic studies of novel self-contacted 2D materials based devices

Eric Stinaff

Department of Physics and Astronomy, Ohio University

Interest in two-dimensional crystals has grown exponentially over the last decade, a testament to their vast technological and scientific potential. In addition to properties such as high mobilities, semiconducting and superconducting behavior, and excellent thermal properties, many of these materials have the potential for novel opto-electronic applications, with large absorption, strong room-temperature emission, non-linear response, and optical control of spin and valley degrees of freedom. In this presentation, we will discuss an experimental investigation of mono-to-few-layer sheets of MoS2 and WS2 employing femtosecond transient absorption spectroscopy (FTAS) and microscopy.

Michael Fisch, Kent State University, X-ray Experiments in Liquid Crystal Science and Technology Mon. October 9th, 2017
12:45 pm-1:45 pm

X-ray Experiments in Liquid Crystal Science and Technology

Michael Fisch

Kent State University

 

The use of X-rays to study liquid crystals has a long history, and is still of continuing interest.  A brief review of liquid crystals and X-ray diffraction from common liquid crystalline phases will be presented.  Interpretation of the resulting diffraction patterns will be discussed, and some of our current experiments in bent-core molecules and “organic salts will be discussed.  The relationship of these studies to current problems in liquid crystal science and technology will be briefly explored,

No seminar, faculty meeting Mon. October 2nd, 2017
12:45 pm-2:00 pm
Maosheng Miao, California State University Northridge, Automatic search versus chemical rules in materials structure study Mon. September 25th, 2017
12:45 pm-1:45 pm

Automatic search versus chemical rules in materials structure study
Maosheng Miao
Department of Chemistry and Biochemistry, California State University Northridge CA,
USA; Beijing Computational Science Research Center, Beijing, China

The increase of the computer power in the past decades not only allow us to calculate
larger systems with higher accuracy in materials studies, but also provide the opportunity
to explore large configuration spaces such as structures and compositions. Automatic
structure searches have been very successful in predicting structures of bulk materials. It
seems out of question whether the automatic search is advantageous over traditional
structure design based on chemical knowledge and intuition.

Liang Wu, UC Berkeley, MPPL3, Antiferromagnetic resonance and in-gap terahertz continuum in Kitaev Honeycomb magnet α−RuCl3 Fri. September 15th, 2017
12:45 pm-1:45 pm

Antiferromagnetic resonance and in-gap terahertz continuum in Kitaev Honeycone magnet α−RuCl3

Spin-1/2 moments in the antiferromagnetic Mott insulator α-RuCl3 are coupled by strongly anisotropic bond-dependent exchange interactions on a honeycomb lattice. Intense study of α- RuCl3 by inelastic scattering has been driven by the proposal that its low energy excitations may be adiabatically connected to the Majorana quasiparticles that emerge in the exact solution of the Kitaev spin liquid model. In my talk, I will present optical absorption measurements using time- domain terahertz spectroscopy in the range 0.3 to 10 meV that reveal several new features of the low-energy spectrum of α-RuCl3 [1].

Liang Wu, University California Berkeley, MPPL2,Giant nonlinear optical responses in Weyl semimetals Tue. September 12th, 2017
11:30 pm-12:30 pm

Giant nonlinear optical responses in Weyl semimetals

Recently Weyl quasi-particles have been observed in transition metal monopnictides (TMMPs) such as TaAs, a class of noncentrosymmetric materials that heretofore received only limited attention. The question that arises now is whether these materials will exhibit novel, enhanced, or technologically applicable properties. The TMMPs are polar metals, a rare subset of inversion- breaking crystals that would allow spontaneous polarization, were it not screened by conduction electrons. Despite the absence of spontaneous polarization, polar metals can exhibit other signatures, most notably second-order nonlinear optical polarizability, leading to phenomena such as second-harmonic generation (SHG).

Liang Wu, University California Berkeley, MPPL1, Low-energy Electrodynamics of 3D Topological Insulators Mon. September 11th, 2017
12:45 pm-1:45 pm

Low-energy Electrodynamics of 3D Topological Insulators

 

Topological insulators (TIs) are a recently discovered state of matter characterized by an “inverted” band structure driven by strong spin-orbit coupling. One of their most touted properties is the existence of robust “topologically protected” surface states.  I will discuss what topological protection means for transport experiments and how it can be probed using the technique of time- domain THz spectroscopy applied to 3D TI thin films of Bi2Se3.  By measuring the low frequency optical response, we can follow their transport lifetimes as we drive these materials via chemical substitution through a quantum phase transition into a topologically trivial regime [1].


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