Skyrmion lattice in Chiral systems

Abstract:

A skyrmion is a topological spin texture, in which the spins point in all of the directions wrapping a sphere. Skyrmion lattice state has been predicted in theory to appear in Chiral systems and is anticipated to play a vital role in quantum magneto-transport processes such as the quantum Hall and topological Hall effects. In this talk, I review the recent year discoveries of SkX in several Chiral systems such as MnSi, Co doped FeSi and FeGe.

Time: Nov. 27, Tuesday, noon.

Location: Rm. 435, Nicholson Hall.

Foods and drinks will be provided.

Nov. 20 Club Meeting: Joseph Prestigiacomo

Topic to be discussed:
Glassy Dynamics of the Superconductor-Insulator Transition of Ultrathin Granular Al Films in a Parallel Magnetic Field

Abstract:
The investigation of the dynamics in glassy systems (magnetic spin glass, electron glass, etc.) have proven to be very useful in understanding the connections between non-equilibrium behavior and their microscopic origins.  In this talk, I review a relatively overlooked system exhibiting slow glassy dynamics, the first-order superconductor-insulator transition of ultrathin granular aluminum films in a parallel magnetic field.  These films may constitute a new class of glassy system, a Josephson glass.

Time: Nov. 20, Tuesday, noon.

Location: Rm. 435, Nicholson Hall.

Foods and drinks will be provided.

Nov. 13 Club Meeting: Dr. Ziyang Meng

Topic To be discussed:
Using entanglement entropy to study quantum phase transitions

Abstract:
In recent years, the concept of entanglement entropy has been introduced into the study of condensed matter system. Entanglement entropy can be used to characterize classical and quantum phase transitions, as well as novel quantum states which are not belong to the Landau-Ginzburg symmetry-breaking paradigm. In this talk, the concept of entanglement, entanglement entropy, and area law will be introduced in a pedagogical manner. Furthermore, the numeric implement of the measurement of entanglement entropy will be discussed within the context of quantum Monte Carlo simulations. An concrete example in quantum spin system, where the entanglement entropy has been applied to characterize the quantum phase transition is demonstrated.

References

Roger Melko
http://online.kitp.ucsb.edu/online/fragnets_c12/melko
Tarun Grover
http://online.kitp.ucsb.edu/online/fragnets_c12/grover
Xiao-Gang Wen
http://online.kitp.ucsb.edu/online/fragnets_c12/wen

Time: Nov. 13, Tuesday, noon.

Location: Rm. 435, Nicholson Hall.

Foods and drinks will be provided.

Characterizing Localized States

Abstract:

The Anderson model of localization continues to attract much attention, and the role of disorder in the metal insulator transition is still a matter of debate.  In this talk, I will review the result of Anderson for localization in disordered models, and then discuss the role of "rare" fluctuation events.  I will then talk about the parameters that have been proposed to characterize these localized states and the numerical results that have been obtained.

Time: Nov. 6, Tuesday, noon.

Location: Rm. 435, Nicholson Hall.

Foods and drinks will be provided.