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Roman O. Rezaev

Publications and source records attributed to Roman O. Rezaev.

3 recordsLinked to original sources
arXiv2017

Superconducting Micro- and Nanohelices

Superconducting micro- and nanohelices are proposed for the first time. A theoretical investigation of the superconducting state in the helical coils at the micro- and nanoscale is performed within the time-dependent Ginzburg-Landau approach. The pattern and number of vortices in a stationary distribution are determined by their confinement to the ultrathin helical spiral and can therefore be efficiently controlled by the helical stripe width and the helical pitch distance for both dense and sparse helices. Quasi-degeneracy of vortex patterns is manifested in the helical spiral when the number of vortices is incommensurable with the total number of half-turns. With increasing radius, superconducting helical spirals provide a physical realization of a transition from the vortex pattern peculiar to an open tube to that of a planar stripe.

cond-mat.supr-con↗
arXiv2012

Monolithic growth of ultra-thin Ge nanowires on Si(001)

Self-assembled Ge wires with a height of only 3 unit cells and a length of up to 2 micrometers were grown on Si(001) by means of a catalyst-free method based on molecular beam epitaxy. The wires grow horizontally along either the [100] or the [010] direction. On atomically flat surfaces, they exhibit a highly uniform, triangular cross section. A simple thermodynamic model accounts for the existence of a preferential base width for longitudinal expansion, in quantitative agreement with the experimental findings. Despite the absence of intentional doping, first transistor-type devices made from single wires show low-resistive electrical contacts and single hole transport at sub-Kelvin temperatures. In view of their exceptionally small and self-defined cross section, these Ge wires hold promise for the realization of hole systems with exotic properties and provide a new development route for silicon-based nanoelectronics.

cond-mat.mtrl-sci↗