National Repository of Grey Literature 3 records found  Search took 0.01 seconds. 
Relativistic spintronic effects in semiconductor structures
Nádvorník, Lukáš ; Jungwirth, Tomáš (advisor) ; Ramsay, Andrew (referee) ; Veis, Martin (referee)
The spin transport and dynamics of optically injected spin polarized carri- ers are studied with a high spatial and/or time resolution in semiconductor GaAs-based heterostructures in multiple transport regimes. An unexpectedly long-scale and high-speed spin diffusion transport is observed in a long-lived electron sub-system induced optically at an undoped single GaAs/AlGaAs heterointerface. A diffusion and drift-dominated spin transport is investi- gated using an electrical spin-detection via the inverse spin Hall effect in doped GaAs-based systems at room and low temperatures. It is shown that the inverse spin Hall signal and the spin transport parameters can be con- trolled by a direct application of an electric field or by expanding a depleted zone of a planar pn-junction.
Study of terahertz radiation emitted using spintronic effects
Jechumtál, Jiří ; Nádvorník, Lukáš (advisor) ; Kašpar, Zdeněk (referee)
Effective emission of picosecond terahertz (THz) pulses using optical femtosecond pul- ses is the basis of THz spectroscopy in the time domain. Recent studies have shown that ultrafast optical excitation of thin metal magnetic multilayers leads to effective emission of THz pulses by converting the spin current to electric current. This work focuses on deter- mining the absolute emission and conversion efficiency of spintronic emitters from several manufacturers. Our comparison suggests that efficiency comparable to highly optimized spintronic emitters can be achieved by utilizing multilayer manufacturing capabilites of the Faculty of Mathematics and Physics of Charles University. The work also demon- strates the significant influence of interface quality on the throughput of ultrafast spin currents. Furthermore, the work describes a saturation effect observed in the relation be- tween emission and optical excitation fluency, which defines suitable excitation conditions for scaling the THz emission to higher electric fields. The observed spectral dependence of emission on fluence complements the discussion about the nature of ultrafast spin current formation. 1
Relativistic spintronic effects in semiconductor structures
Nádvorník, Lukáš ; Jungwirth, Tomáš (advisor) ; Ramsay, Andrew (referee) ; Veis, Martin (referee)
The spin transport and dynamics of optically injected spin polarized carri- ers are studied with a high spatial and/or time resolution in semiconductor GaAs-based heterostructures in multiple transport regimes. An unexpectedly long-scale and high-speed spin diffusion transport is observed in a long-lived electron sub-system induced optically at an undoped single GaAs/AlGaAs heterointerface. A diffusion and drift-dominated spin transport is investi- gated using an electrical spin-detection via the inverse spin Hall effect in doped GaAs-based systems at room and low temperatures. It is shown that the inverse spin Hall signal and the spin transport parameters can be con- trolled by a direct application of an electric field or by expanding a depleted zone of a planar pn-junction.

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