Abstract
We study the impact of the direction of magnetic flux on the electron motion in GaAs/InAs core/shell nanowires. At small tilt angles, when the magnetic field is aligned nearly parallel to the nanowire axis, we observe Aharonov–Bohm type h/e flux periodic magnetoconductance oscillations. These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell. With increasing tilt of the nanowire in the magnetic field, the flux periodic magnetoconductance oscillations disappear. Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles. We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.
Highlights
We study the impact of the direction of magnetic flux on the electron motion in GaAs/InAs core/shell nanowires
The universal conduction fluctuations (UCF) appear as consequence of electron wave packet interference, but only if the sample dimensions are of the same order or smaller than the phase coherence length of the sample
We have measured the magnetoconductance of GaAs/InAs core/shell nanowires at different tilt angles between nanowire axis and the external magnetic field direction to show the great potential angle resolved measurements offer to resolve electron motion in nanowires
Summary
GaAs/InAs core/shell nanowires were grown using a self-assisted approach by molecular beam epitaxy, without using a foreign growth catalyst such as gold and without addition of dopants[8]. In the second growth step, the GaAs nanowire cores were overgrown with an InAs shell. The substrates were diced into smaller pieces and glued and bonded into chip carriers These pieces were aligned manually within the chip carriers to have a parallel orientation of the nanowire axis and the magnetic field direction in the cryostat later on. Misalignments during this step were checked using SEM and could be determined with about 3° accuracy. Due to small misalignments during the placement of the sample pieces described above, a perfect parallel alignment of the nanowire axis with the direction of the magnetic field was not possible on these samples. 50 μV and measuring the current through the nanowire using a low noise I/V-converter and standard lock-in technique
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