Physics Colloquium Series - Fall 2018

Contact: Dr. Edwin Fohtung, 575-646-5631, efohtung@nmsu.edu

August
*TBA*
	Thursday, August 23, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Abstract TBA Back to top
*TBA*
	Thursday, August 30, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Abstract TBA Back to top

September
*TBA*
	Thursday, September 6, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Abstract Back to top
*Strain and Polarization Dynamics in Energy and Electronic Materials Through Novel X-Ray Imaging Techniques*
Dr. Anastasios Pateras, Department of Materials Science and Engineering, University of Wisconsin-Madison	Thursday, September 13, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Dr. Edwin Fohtung Abstract Ferroelectrics and multiferroics are promising materials for the development of novel electronic devices with unprecedented properties1. To perfectly control them, two are the big questions to be answered: how does the nanoscale crystal structure influences their macroscopic properties, and what physical mechanisms dominate their behavior to different external stimuli? Tightly focused coherent x-ray nanobeams can reveal the atomic structure of crystalline thin films and heterostructures through strain-imaging approaches that solve the phase problem of x-ray crystallography with the use of iterative algorithms. Current modeling approaches are widely based on the kinematical theory of x-ray diffraction and, therefore, are limited to investigating thin layers with thicknesses below the x-ray extinction depth2,3. By considering primary extinction and multiple scattering in the interaction of x-rays with crystals, state-of-the-art strain imaging techniques can be extended to incorporate dynamical diffraction directly inside a phase retrieval algorithm. This opens new opportunities for using coherent x-ray nanobeams for the structural investigation of quantum and energy materials systems that could not be thought before. ∗ Electronic address: apateras@wisc.edu 1 S. Valencia, A. Crassous, L. Bocher, V. Garcia, X. Moya, R. O. Cherifi, C. Deranlot, K. Bouzehouane, S. Fusil, A. Zobelli, A. Gloter, N. D. Mathur, A. Gaupp, R. Abrudan, F. Radu, A. Barth´el´emy, and M. Bibes, Nature Materials 10, 753 (2011). 2 A. Pateras, J. Park, Y. Ahn, J. A. Tilka, M. V. Holt, H. Kim, L. J. Mawst, and P. G. Evans, Physical Review B 97, 235414 (2018). 3 A. Pateras, J. Park, Y. Ahn, J. A. Tilka, M. V. Holt, C. Reichl, W. Wegscheider, T. A. Baart, J. P. Dehollain, U. Mukhopadhyay, L. M. K. Vandersypen, and P. G. Evans, Nano Letters 18, 2780 (2018). Back to top
*TBA*
	Thursday, September 20, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Abstract TBA. Back to top
*TBA*
	Thursday, September 27, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Abstract TBA. TBD. Back to top

October
*Non-Destructive Isotope Specific Tomography Using Energy-Resolved Neutron Imaging*
Dr. Adrian Losko, LANSCE, Los Alamos National Laboratory	Thursday, October 4, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Dr. Heinz Nakotte Abstract Epithermal neutrons offer an excellent probe for samples that do not provide sufficient penetration for X-rays or thermal neutrons. Neutron imaging measurements are performed at reactors or pulsed sources but the inherent energy resolution implicit at short pulsed neutron sources offers unique opportunities. Combined with advancement in Time-of- Flight 2D neutron detection, new capabilities of material characterization using energy-resolved neutron imaging and computed tomography that enable isotope specific imaging by deriving areal isotope densities from transmission spectra exhibiting neutron resonances is possible. Tomographic algorithms allow 3D reconstructions of the spatial distribution of isotopes, density and features in cm-sized samples. We present recent advances at the Los Alamos Neutron Science Center, which provides the infrastructure for actinides and radioactive samples to apply this technique for instance to nuclear fuels, non-proliferation and weapons materials. The potential application of this technique for nondestructive examination of irradiated nuclear fuel is under consideration. Abstract TBA Back to top
*TBA*
	Thursday, October 11, 4:00–5:00 p.m. Gardiner Hall, Room 230 Host: Abstract TBA Back to top
*Magnetic Properties of Hybrid Systems*
Dr. Jose de la Venta, Department of Physics Colorado State University	Thursday, October 18, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Dr. Edwin Fohtung Abstract Hybrid magnetic heterostructures allow the engineering of new material properties by creative uses of proximity effects. When two dissimilar materials are in close physical proximity the properties of each one may be radically modified or occasionally a completely new material emerges. By properly designing hybrid ferromagnet/oxides new magnetic properties arise unlike any known magnetic materials. In a series of recent studies, we have investigated the static and dynamic magnetic properties of different hybrids of ferromagnets and vanadium oxides. The vanadium oxides (VO2 and V2O3) are canonical examples of materials showing a first order structural phase transition and a metal to insulator transformation. Static properties such as the coercivity, anisotropy and magnetization and dynamical properties such as the microwave response are modified by the proximity effects. Our results indicate that the structural transformation and the nanoscale phase coexistence across the first-order phase transition of the oxides are responsible for the observations in these hybrid materials. The results suggest the existence of similar effects in other hybrid materials and give rise to interesting perhaps useful properties. TBD. Back to top
*TBA*
	Thursday, October 25, 4:00 - 5:00 p.m. Gardiner Hall, Room 230 Host: Abstract TBD. Back to top

November

TBA

Thursday, November 1, 4:00 - 5:00 p.m.
Gardiner Hall, Room 230
Host:

Abstract

TBA

Dr. Michael Fitzsimmons Oakride National Laboratory & the University of Tennessee

Thursday, November 8, 4:00 - 5:00 p.m.
Gardiner Hall, Room 230
Host: Dr. Edwin Fohtung

Abstract

Materials Informatic and Discovery

Dr. Taylor D. Sparks
University of Utah

Thursday, November 15, 4:00 - 5:00 p.m.
Gardiner Hall, Room 230
Host: Dr. Boris Kiefer

Abstract

No Colloquium on Nov 22: THANKS GIVING HOLIDAYS!!

TBA

Dr. Zhongbo Kang

Physics Department, UCLA

Thursday, November 29, 4:00 - 5:00 p.m.
Gardiner Hall, Room 230
Host: Dr. Marc Schlegel

Abstract

December

TBA

Dr. Srinivasa Singamaneni

Thursday, December 6, 4:00 - 5:00 p.m.
Gardiner Hall, Room 230
Host: Dr. E. Fohtung

Abstract