Fyzikální ústav Akademie věd ČR

Semináře

Úterý, 30.05.2017 10:00

Rubén Pérez (Scanning Probe Microscopy Theory & Nanomechanics Group ; Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain , http://www.uam.es/spmth/ )

The talk will start with a brief summary of the research activity of the SPMTH group, in particular, our recent developments to describe tip-sample transport and interactions for the simulation of STM and AFM [1,2], reducible oxides for catalysys and optoelectronics [3], graphene edge states and vacancy-induced magnetism [4], and the challenges involved in the imaging of surfaces and large biomolecules in their native liquid environment [5,6].

Úterý, 30.05.2017 15:00 - 16:00

František Slanina (Department of Condensed Matter Theory, FZÚ AV ČR, v.v.i.)

Abstract: The work is motivated by experiments on localization of classical waves. i. e. light and sound, in random media. Especially we have in mind granular materials, where waves travel along complex structures of force chains. These force chains are modelled by random graphs of various types. We investigate first the most classical Erdős-Rényi graph ensemble and then compare it to random regular (especially cubic) graphs and to scale-free bipartite graphs. The methodology is based on exact diagonalization of large samples.

Pátek, 02.06.2017 10:00 - 11:30

Alexey Belyanin (Texas A&M University)

Relativistic Dirac and Weyl fermions were extensively studied in quantum field theory. Recently they emerged in the nonrelativistic condensed-matter setting as gapless quasiparticle states in some types of crystals. Notable examples of 2D systems include graphene and surface states in topological insulators such as Bi2Se3. Their 3D reincarnation is Dirac and Weyl semimetals that were recently discovered experimentally. Most of the research has been focused on their topological properties and electron transport. However, their optical and plasmonic properties are no less exciting. Optical phenomena can provide valuable insight into the fascinating physics of these materials. Moreover, their unique optical properties can be utilized in future optoelectronic devices. I will discuss several examples illustrating these points. They include plasmons and polaritons in Weyl semimetals, nonlinear optical response of graphene and topological insulators in the infrared and THz range, nonlinear generation of THz plasmons, and optical properties of chiral Dirac/Weyl fermions in a quantizing magnetic field.

Středa, 07.06.2017 10:00 - 11:00

Paul S. Weiss (Distinguished Professor of Chemistry & Biochemistry and of Materials Science & Engineering, UCLA)

We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to explore the ultimate limits of miniaturization. We direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales.

Úterý, 13.06.2017 10:00 - 11:00

Karina Morgenstern (Chair of Physical Chemistry I; Ruhr-Universität Bochum, Germany)

While photochemistry in the gas phase demands a resonant excitation of the molecules, the presence of a metal surface in surface chemistry opens a different pathway via the creation of hot electrons in the metal and subsequent attachment of these energetic electrons to adsorbed molecules. We use two set-ups that combine a low-temperature scanning tunneling microscope operating below 10 K with a frequency doubled femto-second laser and a tunable pico-second laser, respectively, to investigate processes induced by these electrons on a single molecule basis.

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