Seminars and Colloquia, July through December, 2016


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Seminars and Colloquia, Typical Week:


Oklahoma High Energy Physics Seminar on Talk-Back Television:

Date:Thursday
Time:1:30-3:00 PM
Place:106 B Studio Room, Classroom Building, OSU
& Nielsen Hall, Room 103, OU
Inquiries: kaladi.babu@okstate.edu or kao@nhn.ou.edu

Physics Colloquium:

Date:Thursday
Time:3:30-4:30 PM
Place:PS 110
Inquiries: TBA@okstate.edu or perk@okstate.edu

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

Date:Friday (bi)weekly
Time:2:30 PM
Place:PS 147
Inquiries: perk@okstate.edu

Oklahoma State Physics Department

Seminars and Colloquia, July 4-8, 2016


Physics PhD Thesis Defense:

Speaker:Saki Khan
Department of Physics
Oklahoma State University
Date:Thursday, July 7, 2016
Time:2:00 PM
Place:PS 147
Title:Unification and Physics Beyond Standard Model

Physics PhD Thesis Defense:

Speaker:Jiating Ni
Department of Physics
Oklahoma State University
Date:Thursday, July 8, 2016
Time:9:00 AM
Place:PS 147
Title:Initial State Dependance of a Quantum Ratchet

Oklahoma State Physics Department

Seminars and Colloquia, July 11-15, 2016


Physics PhD Thesis Defense:

Speaker:Khoa Bui
Department of Physics
Oklahoma State University
Date:Thursday, July 12, 2016
Time:2:00 PM
Place:PS 147
Title:Induced Transparency and Pulse Delay Plus Induced Absorption and Pulse Advancement Using the Orthogonally Polarized Whispering Gallery Modes of a Single Microresonator

Oklahoma State Physics Department

Seminars and Colloquia, July 18-22, 2016


No talks scheduled.


Oklahoma State Physics Department

Seminars and Colloquia, July 25-29, 2016


No talks scheduled.


Oklahoma State Physics Department

Seminars and Colloquia, August 1-5, 2016


No talks scheduled.


Oklahoma State Physics Department

Seminars and Colloquia, August 8-12, 2016


No talks scheduled.


Oklahoma State Physics Department

Seminars and Colloquia, August 15-19, 2016


First Week of Classes


Joint Physics Colloquium and Chemistry Seminar:

Speaker:Dr. Pavel V. Avramov
Department of Chemistry and Green-Nano Materials Research Center
Kyungpook National University, Daegu, South Korea
Date:Thursday, August 18, 2016
Time:3:30 PM
Place:PS 110
Title:Quantum Stability of Low-Dimensional Nanostructures: The Limitations of Periodic Boundary Conditions

Abstract:

Quantum stability of atomic and electronic structure of low-dimensional structures is the key point since the discovery of a variety of 1D and 2D nanowires, nanotubes, one-atom thick films (e.g. graphene and h-BN) and complex low-dimensional heterostructures. The great progress to describe and interpret the structure and properties of low-dimensional nanostructures has been achieved by electronic structure calculations of perfect 1D and 2D infinite crystalline lattices, for which an implementation of periodic boundary condition approximation can cause artificial structural and magnetic order stabilization. There are several basic mechanisms of structural and magnetic order instability of low-dimensional structures. In particular, quantum destabilization of atomic structure of low-dimensional nanoclusters with multiple non-equivalent sublattices can be caused by translation symmetry breakdown. The asymmetry of zig-zag h-BN, h-SiC or fluorinated nanoribbon edges causes a uniform structural curvature with considerable out-of-the-plane bending, which results in breakdown of translational periodicity. Another mechanism of translational symmetry breakdown in low-dimensional carbon pentagon-constituted nanostructures with multiple sp2/sp3 sublattices. It was found that finite nanoclusters suffer strong uniform unit cell bending followed by breaking of the crystalline lattice linear translation invariance. At one-electron level of theory, a perfectly flat lattice is just a regular point on a potential energy surface with non-zero derivative, rather than an extreme point like global or local minimum or transition state. The lattice bending along two perpendicular directions leads to formation of nanotubes with potential energy crossing at zero curvature. Application of von Neumann–Wigner theorem to large-diameter tubes proves that 2D sp2/sp3 nanostructures are correlated transition states between two symmetrically equivalent bent structures.

Note: Refreshments will be served in Physical Sciences Room 147 at 3:00 PM.


Oklahoma State Physics Department

Seminars and Colloquia, August 22-26, 2016


Second Week of Classes


Oklahoma State Physics Department

Seminars and Colloquia, August 29-September 2, 2016


Condensed Matter Physics Seminar:

Speaker:Dr. Mario F. Borunda
Department of Physics
Oklahoma State University
Date:Friday, September 2, 2016
Time:1:00 PM
Place:PS 148, OSU
& Nielsen Hall, Room 103, OU
Title:Raman Spectroscopy in Graphene

Abstract:

Raman spectroscopy plays a key role in studies of graphene and related carbon systems. Graphene is perhaps the most promising material of recent times for many novel applications, including electronics. In this talk, I will present how the traditional and well established Kramers–Heisenberg–Dirac (KHD) Raman scattering theory (1925–1927) was extended to crystalline graphene.


Oklahoma State Physics Department

Seminars and Colloquia, September 5-9, 2016


Labor Day Break: Monday, September 5


Physics Colloquium:

Speaker:Dr. Gregory J. Quarles
Chief Scientist
The Optical Society (OSA), Washington, DC
Date:Thursday, September 8, 2016
Time:3:30 PM
Place:PS 110
Title:TBA

Dr. Quarles is the 2016 Physics Distinguished Alumni & Hall of Fame Inductee.


Oklahoma State Physics Department

Seminars and Colloquia, September 12-16, 2016



Oklahoma State Physics Department

Seminars and Colloquia, September 19-23, 2016



Oklahoma State Physics Department

Seminars and Colloquia, September 26-30, 2016


Physics Colloquium:

Speaker:Dr. Congjun Wu
Department of Physics
University of California at San Diego
Date:Thursday, September 29, 2016
Time:3:30 PM
Place:PS 110
Title:Novel Orbital Phases of Cold Atoms in Optical Lattices — Unconventional BEC and Itinerant Ferromagnetism

Abstract:

Orbital is a degree of freedom independent of charge and spin, which plays important roles in magnetism and superconductivity in transition-metal-oxides. Recently, cold atom optical lattices have provided a new opportunity to investigate orbital physics. In this talk, we will present novel features of orbital physics that are not easily accessible in solid state systems.

We predicted that bosons, when pumped into high orbital bands of optical lattices, exhibit a class of novel superfluid states with complex-valued condensate wavefunctions spontaneously breaking time-reversal symmetry. These states are beyond the scope of the “no-node” theorem which applies to most well-known states of bosons. They exhibit unconventional symmetries in analogy to those of unconventional superconductivity. Our prediction has been experimentally observed by Hemerich’s group at Hamburg, who verified the p-wave symmetry through matter-wave interference and time-of-flight measurements. For orbital fermions, we focus on itinerant ferromagnetism (FM), i.e. FM with Fermi surfaces, which is a hard-core problem of strong correlation physics. The mean-field type Stoner criterion neglects correlation effects and thus too much overestimates the FM tendency. In fact, even under very strong repulsions, typically electrons in solids usually remain paramagnetic. Furthermore, the Curie–Weiss metal phase above Curie temperature is also a long-standing problem exhibiting a dichotomic nature: The spin channel is local moment-like and incoherent while the charge channel remains coherent. In spite of these difficulties, based on unambiguous non-perturbative studies, we predict the existence of the itinerant FM phase with high Curie temperatures in the p-orbital bands. We established a series of theorems proving the ground state FM phase over a large region of fermion fillings and performed sign-problem free quantum Monte-Carlo simulations. The critical and finite-size scalings of magnetic phase transitions are performed based on which Curie temperatures are extracted at high numeric precisions. Our results also apply to certain types of d-orbital transition-metal oxides in solid state systems.

  1. Congjun Wu, Unconventional Bose–Einstein Condensations Beyond the “No-node” Theorem, Mod. Phys. Lett. 23, 1 (2009), a brief review.
  2. Yi Li, E. H. Lieb, Congjun Wu, Exact Results on Itinerant Ferromagnetism in Multi-orbital Systems on Square and Cubic Lattices, Phys. Rev. Lett. 112, 217201 (2014).
  3. Shenglong Xu, Yi Li, Congjun Wu, Thermodynamic properties of a 2D itinerant ferromagnet — a sign-problem free quantum Monte Carlo study, Phys. Rev. X 5, 021032 (2015).

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:00 PM. All students are welcome! Refreshments will be served.


Oklahoma State Physics Department

Seminars and Colloquia, October 3-7, 2016



Oklahoma State Physics Department

Seminars and Colloquia, October 10-14, 2016



Fall Break: Friday, October 14


Oklahoma State Physics Department

Seminars and Colloquia, October 17-21, 2016



Oklahoma State Physics Department

Seminars and Colloquia, October 24-28, 2016



Oklahoma State Physics Department

Seminars and Colloquia, October 31-November 4, 2016



Oklahoma State Physics Department

Seminars and Colloquia, November 7-11, 2016



Oklahoma State Physics Department

Seminars and Colloquia, November 14-18, 2016



Oklahoma State Physics Department

Seminars and Colloquia, November 21-25, 2016


Thanksgiving Break: November 23-25


Oklahoma State Physics Department

Seminars and Colloquia, November 28-December 2, 2016



Oklahoma State Physics Department

Seminars and Colloquia, December 5-9, 2016


Prefinals Week

No talks scheduled


Oklahoma State Physics Department

Seminars and Colloquia, December 12-16, 2016


Finals Week

No talks scheduled


Oklahoma State Physics Department

Seminars and Colloquia, December 19-23, 2016


No talks scheduled


Oklahoma State Physics Department

Seminars and Colloquia, December 26-30, 2016


No talks scheduled


Last Updated:

jhhp@jperk.phy.okstate.edu