The Söllerhaus-Workshop 2014 of the 2^nd Institute of Physics was a great success.

The Master College Physics in Aachen has now a facebook site:
www.facebook.com/pages/RWTH-Masters-College-Physics/557850200956299

Appl. Phys. Lett. 104, 062406 (2014)
We demonstrate all-electrical spin generation and subsequent manipulation by two successive electric field pulses in an n-InGaAs heterostructure in a time-resolved experiment at zero external magnetic field. The first electric field pulse along the [110] crystal axis creates a current-induced spin polarization (CISP) which is oriented in the plane of the sample. The subsequent electric field pulse along [110] generates a perpendicular magnetic field pulse leading to a coherent precession of this spin polarization with 2-dimensional electrical control over the final spin orientation. Spin precession is probed by time-resolved Faraday rotation. We determine the build-up time of CISP during the first field pulse and extract the spin dephasing time and internal magnetic field strength during the spin manipulation pulse.

Nanotechnology 25, 035703 (2014)
We report on the influence of low gamma irradiation on the noise properties of individual carbon nanotube (CNT) field-effect transistors (FETs) with different gate configurations and two different dielectric layers, SiO₂ and Al₂O₃. Before treatment, strong generation–recombination noise components are observed. These data are used to identify several charge traps related to dielectric layers of the FETs by determining their activation energy. Investigation of samples with a single SiO₂ dielectric layer as well as with two dielectric layers allows us to separate traps for each of the two dielectric layers. We reveal that each charge trap level observed in the side gate operation splits into two levels in top gate operation due to a different potential profile along the CNT channel. After gamma irradiation, only reduced flicker noise is registered in the noise spectra, which indicates a decrease of the number of charge traps. The mobility, which is estimated to be larger than 2 × 10⁴cm²V⁻¹s⁻¹ at room temperature, decreases only slightly after radiation treatment, demonstrating high radiation hardness of the CNTs. Finally, we study the influence of Schottky barriers at the metal–nanotube interface on the transport properties of FETs, analyzing the behavior of the flicker noise component.

Phys. Status Solidi B (2014)
During the past years, there has been renewed interest in the wide-bandgap II–VI semiconductor ZnO, triggered by promising prospects for spintronic applications. First, ferromagnetism was predicted for dilute magnetic doping. In a comprehensive investigation of ZnO:Co thin films based on the combined measurement of macroscopic and microscopic properties, we find no evidence for carrier-mediated itinerant ferromagnetism. Phase-pure, crystallographically excellent ZnO:Co is uniformly paramagnetic. Superparamagnetism arises when phase separation or defect formation occurs, due to nanometer-sized metallic precipitates. Other compounds like ZnO:(Li,Ni) and ZnO:Cu do not exhibit indication of ferromagnetism. Second, its small spin–orbit coupling and correspondingly large spin coherence length makes ZnO suitable for transporting or manipulating spins in spintronic devices. From optical pump/optical probe experiments, we find a spin dephasing time of the order of 15 ns at lowtemperatures, which we attribute to electrons bound to Al donors. In all-electrical magnetotransport measurements, we successfully create and detect a spin-polarized ensemble of electrons and transport this spin information across several nanometers. We derive a spin lifetime of 2.6 ns for these itinerant spins at low temperatures, corresponding well to results from an electrical pump/optical probe experiment.

Cover image of IoP Nanotechnology, Vol. 24; (article at p. 444001) 2013, C. Neumann, et al., "Graphene-based charge sensors".

Die Europäische Kommission hat Graphene als eines von zwei FET Flagship Projekten ausgewählt, welche über einen Zeitraum von 10 Jahren verteilt ein Fördervolumen von jeweils bis zu 1 Mrd. Euro erhalten sollen. Das Ziel des Graphene-Flagship Projektes ist eine rasche wirtschaftliche Nutzung von Graphen und ähnlichen zwei-dimensionalen Materialien in den Bereichen Informations- und Telekommunikationstechnologie, Materialwissenschaft, Energie und Life-Science.
Pressemitteilung der RWTH
Fernsehbericht der Deutschen Welle vom 10.02.2013