Hilde Hardtdegen | Searcharxiv

arXiv2012

Scanning tunneling microscopy with InAs nanowire tips

Indium arsenide nanowires grown by selective-area vapor phase epitaxy are used as tips for scanning tunneling microscopy (STM). The STM tips are realized by positioning the wires manually on the corner of a double cleaved gallium arsenide wafer with submicrometer precision and contacting them lithographically, which is fully compatible with further integrated circuitry on the GaAs wafer. STM images show a z-noise of 2 pm and a lateral stability of, at least, 0.5 nm on a Au(111) surface. I(z) spectroscopy reveals an exponential decay indicating tunneling through vacuum. Subsequent electron microscopy images of the tip demonstrate that the wires are barely modified during the STM imaging.

cond-mat.mes-hall↗

arXiv2007

Weak antilocalization in high mobility Ga(x)In(1-x)As/InP two-dimensional electron gases with strong spin-orbit coupling

We have studied the spin-orbit interaction in a high mobility two-dimensional electron gas in a GaInAs/InP heterostructure as a function of an applied gate voltage as well as a function of temperature. Highly sensitive magnetotransport measurements of weak antilocalization as well as measurements of Shubnikov--de Haas oscillations were performed in a wide range of electron sheet concentrations. In our samples the electron transport takes place in the strong spin precession regime in the whole range of applied gate voltages, which is characterized by the spin precession length being shorter than the elastic mean free path. The magnitude of the Rashba spin-orbit coupling parameter was determined by fitting the experimental curves by a simulated quantum conductance correction according to a model proposed recently by Golub [Phys. Rev. B 71, 235310 (2005)]. A comparison of the Rashba coupling parameter extracted using this model with the values estimated from the analysis of the beating pattern in the Shubnikov--de Haas oscillations showed a good agreement.

cond-mat.mes-hall↗