Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 29: Poster Session: Spintronics; Spin-controled transport; Topological insulators; Interfaces / Surfaces; Magnetic semiconductors

HL 29.25: Poster

Montag, 11. März 2013, 16:00–20:00, Poster A

Milli-Kelvin transport experiments on GaAs/(Ga,Mn)As core-shell nanowires — •Christian Butschkow¹, Elisabeth Reiger¹, Andreas Rudolph¹, Stefan Geißler¹, Dieter Schuh¹, Werner Wegscheider², and Dieter Weiss¹ — ¹Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany — ²ETH Zürich, 8093 Zürich, Switzerland

We performed transport measurements on ferromagnetic GaAs/(Ga,Mn)As core-shell nanowires at temperatures T<1K. These nanowires were grown in a bottom-up process using molecular beam epitaxy and the Vapor-Liquid-Solid technique. The nanowires show a length of up to 4.5µm at a diameter of ∼100nm and a shell thickness of ∼30nm. For T<200mK we observe a pronounced localization of charge carriers resulting in an increase of the resistance by two orders of magnitude. This localization can be suppressed by applying a finite bias voltage or an external magnetic field. Additionally we observe conductance oscillations as a function of the magnetic field. The oscillations are observable for T<900mK, with increasing amplitude at lower temperatures. Considering previous investigations on (Ga,Mn)As nanostructures, fabricated lithographically from bulk material, it is likely that our observations can be ascribed to phase coherent transport effects. It was shown on lithographically defined nanowires of similar dimensions as the core-shell nanowires, that weak antilocalization like features as well as universal conductance fluctuations are observable [1].

[1] D. Neumaier et al. New Journal of Physics 10, 055016 (2008).