Condensed Matter Seminars

Transient Dynamics of d-Wave Superconductors after a Sudden Excitation

Speaker: 
Francesco Peronaci, International School for Advanced Studies (SISSA), Trieste, Italy
Event Date and Time: 
Thu, 2016-04-21 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Ilya Elfimov
Intended Audience: 
Graduate

Motivated by recent ultrafast pump-probe experiments on high-temperature superconductors, we discuss the transient dynamics of a d-wave BCS model after a quantum quench of the interaction parameter. We find that the existence of gap nodes, with the associated nodal quasiparticles, introduces a decay channel which makes the dynamics much faster than in the conventional s-wave model.

Relaxation and thermalization in many-body systems coupled to different bosonic degrees of freedom

Speaker: 
J. Bonča, University of Ljubljana
Event Date and Time: 
Thu, 2016-04-07 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Mona Berciu
Intended Audience: 
Graduate

In the first part I will briefly overview a fundamental study of the relaxation dynamics of a single hole in the two dimensional t-J model initially excited by a strong quench. Taking fully into account quantum effects we may follow the time-evolution of the system from a highly excited state until it reaches a steady state. Relaxation occurs on the time- scale of 10 f s due to inelastic scattering of a photo-excited carrier on spin excitations [1,2]. This mechanism can explain a finite raise of the scattering rate observed in ultrafast pump-probe experiments on cuprates [2].

In-situ Investigation of Growth and Superconductivity of Single-Layer FeSe Films on SrTiO3

Speaker: 
Jianfeng Ge (Shanghai Jiao Tong University)
Event Date and Time: 
Mon, 2016-03-07 14:00 - 15:00
Location: 
Ampel 311
Superconductivity with critical temperature above boiling point of nitrogen or even room temperature has been a pursuing goal of researchers ever since its discovery, because of its potential application in future electronic devices. Interface effects were found to induce superconductivity between insulating oxides, as well to enhance critical temperature of superconducting films, which matches the technology of device manufacturing perfectly.

Green function for the nonlinear Luttinger Liquid from nonlinear steepest descent

Speaker: 
Tom Price (Cambridge University, UK)
Event Date and Time: 
Tue, 2016-03-08 14:00 - 15:00
Location: 
Henn 318
Intended Audience: 
Graduate
We discuss the time dependent Green function of the nonlinear Luttinger liquid, using the Fractional Quantum Hall edge as an example. The Green function can be written as a Fredholm determinant, whose long time asymptotics we find by solving an associated Riemann--Hilbert problem using the method of nonlinear steepest descent. The results agree exactly with the mobile impurity model, which has a simple interpretation as a factorization of the solution to the asymptotic Riemann--Hilbert problem.

Photoemission Electron Microscopy for Ultrafast Nano-Optics: Femtoseconds to Attoseconds

Speaker: 
Erik Marsell, Lund University (Sweden)
Event Date and Time: 
Fri, 2016-02-26 14:00 - 15:00
Location: 
AMPEL 311
Nano-optics, the use of nanostructured surfaces for the concentration, manipulation, and application of light on a sub-wavelength scale, is a maturing technology capable of connecting the worlds of photonics and electronics. This opens up possibilities for devices combining the small size currently only found in electronics with the high operating speed offered by photonics. However, the simultaneous small and fast nature of the nano-optical excitations calls for characterization methods with extreme spatiotemporal resolution.

Charge Order in NbSe2

Speaker: 
Felix Flicker (UC Berkeley)
Event Date and Time: 
Wed, 2016-02-10 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Marcel Franz
Intended Audience: 
Graduate

Niobium diselenide has long served as a prototype of two-dimensional charge ordering, believed to arise from an instability of the electronic structure analogous to the one-dimensional Peierls mechanism

Anomalous Dimensions and Unparticles in the Cuprate Superconductors

Speaker: 
Philip Phillips
Event Date and Time: 
Thu, 2016-03-10 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
George Sawatzky
Intended Audience: 
Graduate

High-temperature superconductivity in the cuprates remains an unsolved problem because no knock-down experiment has  revealed unambiguously the nature of the charge carriers in the normal state.

**NOTE LOCATION: AMPEL 311** Atomic Dynamics via meV-Resolution X-Ray Scattering: New Results on High-Temperature Superconductors

Speaker: 
Alfred Baron, Materials Dynamics Laboratory, RIKEN SPring-8 Center
Event Date and Time: 
Thu, 2016-02-25 14:00 - 15:00
Location: 
AMPEL 311
Local Contact: 
George Sawatzky
Intended Audience: 
Graduate

High-resolution inelastic x-ray scattering (IXS) measures atomic motions at THz frequencies over angstrom-scale correlation lengths.

Atomic-resolution studies of materials by aberration-corrected scanning transmission electron microscopy

Speaker: 
Ondrej L. Krivanek, Arizona State University
Event Date and Time: 
Thu, 2016-03-03 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
George Sawatzky
Intended Audience: 
Graduate

Aberration-corrected scanning transmission electron microscopes (STEMs) are now able to form electron probes as small as 0.5 Å in diameter, and they can image and spectroscopically analyze single atoms in-situ.  Nion Co., has pioneered these advances, by developing the first aberration corrector that improved spatial resolution of an electron microscope to better than 1 Å, and later on by developing a new STEM that can acquire images and high quality spectra from single atoms in many different types of materials.  More recently, we have introduced a monochromated STEM system for el

Correlated electrons from the bottom up: application to high-Tc cuprates

Speaker: 
Lucas Wagner, UIUC
Event Date and Time: 
Tue, 2016-02-09 13:00 - 14:00
Location: 
Hennings 318
Local Contact: 
George Sawatzky/Mona Berciu
Intended Audience: 
Graduate

First principles calculations, in which materials are simulated using only fundamental constants, are a powerful way to study electronic structure of materials.

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