Events Archive

SPECIAL Condensed Matter Seminar - Ben Feldman, Harvard University - "Spin and Valley Influence on the Fractional Quantum Hall Effect in Suspended Gra
Fri, Dec 21, 2012, 1:30 pm2:30 pm
Graphene has recently attracted considerable interest because the fourfold spin and valley degeneracy of its charge carriers enables the formation of a rich variety of correlated states at high magnetic field. In this talk, I will discuss electronic compressibility measurements of suspended graphene in the quantum Hall regime. Our measurements…
SPECIAL Condensed Matter Seminar - Inna Vishik, Stanford University - "Phase Competition in Cuprate Superconducting Dome"
Wed, Dec 19, 2012, 1:30 pm2:30 pm
The cuprate high temperature superconductors constitute one of the most difficult problems in condensed matter physics and a detailed experimental phenomenology is a crucial starting point for microscopic understanding. Angle-resolved photoemission spectroscopy (ARPES) measures electronic structure in momentum-space and is a powerful tool for…
Condensed Matter Seminar - Ganpathy Murthy, University of KY - Hamiltonian Theory of Fractionally Filled Chern Bands
Mon, Dec 10, 2012, 1:15 pm2:30 pm
Abstract: When a band of noninteracting electrons has a nontrivial Chern number, it is called a Chern band. When such a band is fully filled, the dimensionless Hall conductance is the Chern number. There is considerable numerical evidence that in the presence of suitable interactions, when a Chern band is fractionally filled, the electrons form…
Condensed Matter Seminar - Tomasz Durakiewicz, Los Alamos National Laboratory - Time-resolved ARPES of f-electron systems
Thu, Nov 29, 2012, 2:00 pm3:30 pm
The coherence temperature, T*, sets an important energy scale in correlated f-electron systems. In this scale the hybridization gap opens at or in the vicinity of the Fermi level and the gap magnitude scales with effective quasiparticle mass. The coherent part of the self-energy corresponding to the gap formation is reduced at high temperatures,…
Condensed Matter Seminar - Michael Fuhrer, University of Maryland - "Surface Conduction of Topological Dirac Electrons in Bulk Insulating Bi2Se3"
Mon, Nov 19, 2012, 1:15 pm2:30 pm
The three dimensional strong topological insulator (STI) is a new phase of electronic matter which is distinct from ordinary insulators in that it supports on its surface a conducting two-dimensional surface state whose existence is guaranteed by topology. I will discuss experiments on the STI material Bi2Se3, which has a bulk bandgap of 300 meV,…
Condensed Matter Seminar - Nuh Gedik, Massachusetts Institute of Technology, " Ultrafast Probing of Dirac Fermions in Topological Insulators"
Mon, Nov 12, 2012, 1:15 pm2:30 pm
The three-dimensional topological insulator (TI) is a new quantum phase of matter that exhibits quantum-Hall-like properties, even in the absence of an external magnetic field. Charge carriers on the surface of a TI behave like a two-dimensional gas of massless helical Dirac fermions for which the spin is ideally locked perpendicular to the…
Condensed Matter Seminar - Kobi Kraus, Weizmann Institute of Science Topological States and Adiabatic Pumping in Quasicrystals
Tue, Oct 23, 2012, 1:15 pm2:30 pm
Abstract: The discovery of topological insulators has sparked considerable interest in the study of topological phases of matter. Yet, realizations of these phases of matter are scarce. In this talk we will show, both theoretically and experimentally, that quasicrystals possess high-dimensional topological phases. We demonstrate that 1D…
Condensed Matter Seminar - Prof Xiao-Liang Qi, Stanford University - "Synthetic non-Abelian anyons in fractional Chern insulators and beyond"
Mon, Oct 22, 2012, 1:15 pm2:30 pm
An exciting new prospect in condensed matter physics is the possibility of realizing fractional quantum Hall states in simple lattice models without a large external magnetic field, which are called fractional Chern insulators. A fundamental question is whether qualitatively new states can be realized on the lattice as compared with ordinary…
Condensed Matter Seminar - Shuichi Murakami, Tokyo Institute of Technology - " Topological magnon transport in ferromagnets"
Tue, Oct 16, 2012, 3:00 pm4:30 pm
Magnons (spin waves) are low-energy excitations in magnets. We theoretically study effects caused by Berry curvature due to magnon band structure in ferromagnetic insulators, in analogy with anomalous Hall and spin Hall effect for electrons. From the semiclassical theory, the Berry curvature causes thermal Hall effect for magnons, and we…
Condensed Matter Seminar - Prof. Tomi Ohtsuki, Sophia University Tokyo, Japan "Simulating Anderson Localization"
Mon, Oct 8, 2012, 1:15 pm2:30 pm
While Anderson localization was predicted more than half a century ago, it remains an active research topic, not only in condensed matter physics, but also in cold atom physics as well as in optical physics. Anderson localization is classified in 10 symmetry classes, according to the basic symmetry of the system such as time reversal…
Condensed Matter Seminar - Adam Nahum, University of Oxford "Loop models, vortex lines, and SU(n) magnets"
Mon, Sep 24, 2012, 1:15 pm2:30 pm
Abstract: I will discuss two apparently disparate types of critical phenomenon which are tied together by the language of loop models. The first arises at geometrical phase transitions in disordered 3D systems with vortex line defects. These defects can undergo percolation-like transitions at which the typical size of a vortex loop diverges, and…
Condensed Matter Seminar - Dr. Justin J.T. Ye, University of Tokyo
Mon, Aug 6, 2012, 1:30 pm2:45 pm
"Driving metal-insulator transitions by liquid gating”

Condensed Matter Seminar, Dr. Sungkun Hong, "Nanoscale Magnetic Imaging Using Single Electronic Spins in Diamond"
Mon, May 21, 2012, 1:00 pm3:00 pm
It has been a long standing goal to detect individual spins with nanoscale spatial resolution. Nitrogen-vacancy (NV) centers have recently been considered as an promising candidate for such sensing, as their spins have long coherence times even at room temperature and are localized on atomic lengthscales. In this talk I will present our…
Condensed Matter Seminar, Gregory A. Fiete, "Interacting topological insulators in oxides"
Mon, May 7, 2012, 1:15 pm2:30 pm
Topological phases of matter have received intense interest over the past few years due to the experimental discovery of time-reversal invariant topological insulators (TI) in two and three dimensions. To date, the materials where TI have been reported are weakly interacting and most (if not all) have been previously predicted with simple band…
Condensed Matter Seminar, Leo Kouwenhoven, " Majorana Fermions in Semiconductor Nanowires"
Fri, Apr 27, 2012, 1:00 pm3:00 pm
Majorana fermions can arise as emergent particles in specially designed nanoscale conductors. We have combined superconductors and semiconducting nanowires with strong spin-orbit interaction. At finite magnetic field we find peaks in the density-of-states at zero-bias. The properties of this zero-bias peak compare well with the predictions for…
Condensed Matter Seminar, Karyn Le Hur, " Many-Bodied Quantum Physics with Photons"
Tue, Apr 24, 2012, 2:00 pm3:30 pm
In this Talk, we survey recent theoretical studies concerning the realization of many-body quantum physics with photons. First we introduce the Jaynes-Cummings lattice model and discuss the emergent Mott-Superfluid transition of light in electromagnetic resonator arrays which are under experimental investigation at Princeton in the group of…
Condensed Matter Seminar, Garnet Chan, Numerical approaches to correlated electrons"
Mon, Apr 23, 2012, 1:15 pm2:45 pm
I will describe current research in our group to develop numerical methods for correlated electrons in systems of interest to chemistry and physics. I will survey a wide variety of techniques studied in our research, some of which are unique to our group, including: DMRG and tensor networks, dynamical mean-field theory and density matrix…
Condensed Matter Seminar, Stephan Mandt, "Transport and non-equilibrium dynamics in optical lattices: from expanding atomic clouds to negative absolut
Mon, Apr 2, 2012, 1:15 pm2:30 pm
Ultracold atoms in optical lattices offer the possibility of exploring transport properties of model Hamiltonians, such as the fermionic Hubbard model. However, here we emphasize that cold atoms can also behave very differently from solids: being e.g. exposed to a gravitational force, a cloud of interacting cold atoms in an optical…
Special Condensed Matter Seminar, Jerome Dubail, "Fractional Quantum Hall Effect: from bulk model wave functions to the edge theory"
Wed, Mar 28, 2012, 3:15 pm4:45 pm
Since the seminal contribution of Laughlin in the early 1980s, a large part of the theoretical work on the FQHE has consisted in cooking up new model wave functions for different filling fractions. One approach, which has subsequently drawn a lot of attention because of its exotic implications (in particular non-abelian statistics), consists in…
Special Condensed Matter Seminar, Benoit Estienne, "D-Algebra Structure of Topological Insulators"
Tue, Mar 27, 2012, 2:45 pm4:00 pm
In the quantum Hall effect, the density operators at different wave-vectors generally do not commute and give rise to the Girvin MacDonald Plazmann (GMP) algebra with important consequences such as ground-state center of mass degeneracy at fractional filling fraction, and W_{1 + \infty} symmetry of the filled Landau levels. We show that the…