Fyzikální ústav Akademie věd ČR

Semináře oddělení 15

Spontaneous coherence in systems of cavity polaritons

Úterý, 7. září 2010 - 10:00 - 11:00

Polaritons in optical microcavities are bosonic quasiparticles with mixed photonic and excitonic properties, allowing for the study of general properties of bosonic gases in the wide range of densities, time scale, spatial scale and temperatures (room temperature Bose-Einstein condensation has been recently reported in GaN). In the unique microcavity lab, we are able to observe the condensation kinetics, condensate flow, topological defects and other phenomena in real time and moreover, the physical properties of the interacting quasiparticles can be tuned through sample fabrication

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Minulé semináře

Anomalous Hall conductivity: local orbitals approach

Pondělí, 24. květen 2010 - 16:00 - 17:00

A theory of the anomalous Hall conductivity based on the properties of single site orbitals is presented. Effect of the finite electron life time is modeled by energy fluctuations of atomic-like orbitals. Transition from the ideal Bloch system for which the conductivity is determined by the Berry phase curvatures to the case of strong disorder for which the conductivity becomes dependent on the relaxation time is analyzed…

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Deformace magnetických látek v homogenním poli.

Pátek, 19. březen 2010 - 13:15 - 14:30

Magnetické kapaliny (ferrofluidy) a magnetické gely jsou suspenze magnetických nanočástic v oleji, ve vodě anebo v gelu, které mají mnoho aplikací již dnes a slibné vyhlídky do budoucna. Když na vzorek takového magnetického materiálu působí magnetické pole, jeho povrch se mění. Koule z této látky se deformuje v elipsoid a na povrchu tlusté vrstvy ferrofluidu vznikají různé makroskopické vzory, tekuté špičky a válce, viz tzv. Rosenzweigova nestabilita (viz obrázek).

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Semiclassical Monte Carlo Simulation of Transport in Spintronic Devices

Středa, 3. březen 2010 - 9:00 - 11:00

Semiclassical Monte Carlo methods have been widely used for carrier transport simulations in microelectronic devices. In the Monte Carlo device simulations the charge carriers are replaced by particles whose semiclassical dynamics is determined by the band structure of the semiconductor. Such an approach is justified for describing the transport at the length scales of realistic devices, where the quantum interference effects are less important.

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Spin pumping in magnetic tunnel junctions and topological insulators: Theory and experiments

Čtvrtek, 25. únor 2010 - 10:00 - 11:00

The pursuit of the second-generation spintronics has been focused on harnessing coherent spin states and their dynamics in metals and semiconductors. The salient examples of phenomena involving both coherent spins and their time evolution is the spin-transfer torque and its reciprocal effect, termed spin pumping because it occurs in the absence on any bias voltage, where microwave driven precessing magnetization of a single ferromagnetic (FM) layer emits pure spin current into adjacent normal metal (N) layers.

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