Growth, structure, and superconducting transport in atomically thin near-single-crystal aluminum films on GaAs(111)A
Oral-In-person
Abstract
2D superconductivity occurs in ultra-thin superconductors, where enhanced quantum fluctuations and disorder significantly affect their superconducting properties. In this work, a few-monolayer Al films were studied to explore superconductivity near the 2D limit.
Ultra-thin Al films grown on GaAs(111)A were structurally characterized using in-situ RHEED and ex-situ synchrotron-radiation(SR) XRD. RHEED patterns exhibited streaky features, indicating the formation of highly ordered Al(111) layers. SR-XRD radial scans revealed broad Al(111) diffraction peaks overlapping with the adjacent GaAs(111) substrate tail. Crystal truncation rod simulations based on few-monolayer-thick Al films successfully reproduced the observed Al(111) peak positions and widths. Azimuthal φ-scans across off-normal Al{111̅} reflections revealed peaks separated by 120°, indicating the single-domain feature.
Superconducting fluctuation effects, preserved by in-situ Al2O3 passivation, were investigated via ex-situ transport measurements. Superconducting transition curves were analyzed using Aslamazov-Larkin and Maki-Thompson fluctuation models, revealing insights into dimensional disorder mechanisms. The critical temperature (Tc) and pair-breaking parameter (δ) were extracted from the fits, showing enhanced scattering in thinner films.
Ultra-thin Al films grown on GaAs(111)A were structurally characterized using in-situ RHEED and ex-situ synchrotron-radiation(SR) XRD. RHEED patterns exhibited streaky features, indicating the formation of highly ordered Al(111) layers. SR-XRD radial scans revealed broad Al(111) diffraction peaks overlapping with the adjacent GaAs(111) substrate tail. Crystal truncation rod simulations based on few-monolayer-thick Al films successfully reproduced the observed Al(111) peak positions and widths. Azimuthal φ-scans across off-normal Al{111̅} reflections revealed peaks separated by 120°, indicating the single-domain feature.
Superconducting fluctuation effects, preserved by in-situ Al2O3 passivation, were investigated via ex-situ transport measurements. Superconducting transition curves were analyzed using Aslamazov-Larkin and Maki-Thompson fluctuation models, revealing insights into dimensional disorder mechanisms. The critical temperature (Tc) and pair-breaking parameter (δ) were extracted from the fits, showing enhanced scattering in thinner films.
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Presenters
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Hsien-Wen Wan
- National Taiwan University