Spin-orbit coupling and phase coherence in InAs nanowires

Abstract

We investigated the magnetotransport of InAs nanowires grown by selective-area metal-organic vapor phase epitaxy. In the temperature range between 0.5 and 30 K reproducible fluctuations in the conductance upon variation in the magnetic field or the backgate voltage are observed, which are attributed to electron interference effects in small disordered conductors. From the correlation field of the magnetoconductance fluctuations the phase-coherence length l is determined. At the lowest temperatures l is found to be at least 300 nm while for temperatures exceeding 2 K a monotonous decrease in l with temperature is observed. A direct observation of the weak antilocalization effect indicating the presence of spin-orbit coupling is masked by the strong magnetoconductance fluctuations. However, by averaging the magnetoconductance over a range of gate voltages a clear peak in the magnetoconductance due to the weak antilocalization effect was resolved. By comparison of the experimental data to simulations based on a recursive two-dimensional Green's-function approach a spin-orbit scattering length of approximately 70 nm was extracted, indicating the presence of strong spin-orbit coupling.

Weak (anti)localization in tubular semiconductor nanowires with spin-orbit coupling

“…If the surface conductive channel is a consequence of Fermi level pinning, the internal Rashba and Dresselhaus SOC can be comparably large and compete with each other. Yet, here we consider the Dresselhaus SOC to be the dominant mechanism as it strongly depends on the confinement due to the matrix element k 2 r which is only a few tens of nanometers in a realistic nanowire [17][18][19]. Also, in a situation where the gate is wrapped around the nanowire, the resulting field is collinear to the internal field and therefore renormalizes the internal Rashba coefficient [35,71,72].…”

“…Axial doping can generate pn heterojunctions [13] or quantum dots [14,15]. In narrow-gap semiconductors such as InAs, InSb, or InN due to Fermi level pinning, the conduction band bends downwards at the surface of the nanowire and an electron accumulation layer is formed [16][17][18][19][20]. However, using suitable * michael1.kammermeier@ur.de dopants the potential profile can be flattened and the electrons uniformly distributed inside of the nanowire [16,19,20].…”

“…It is highly topical among experimentalists to study WL/WAL in semiconductor nanowires [17,[32][33][34][35][36][37][38]. Lacking a more precise theoretical description, many authors are compelled to apply existing theory even though it does not accurately match the system.…”

“…For instance, Refs. [32][33][34][35]38] investigate WL/WAL in 111 InAs nanowires by fitting magnetoconductance data with the formulas of Kurdak et al However, in such systems the transport should be either governed by electron states at the surface due to Fermi level pinning or by states that are extended over the entire volume [16][17][18][19][20]. Both scenarios are not comprised in the theory of Kurdak et al Also, it does not take into account the precise form of the spin-orbit field which has been proven to be significant in 2D systems [39][40][41][42][43].…”

Spin precession and modulation in ballistic cylindrical nanowires due to the Rashba effect

“…25 The presence of spin-orbit coupling was confirmed for InN and InAs semiconductor nanowires by measuring the weak antilocalization effect. [26][27][28][29][30] The various possibilities of spin control in 2DEGs and planar wire structures opened up by the Rashba effect have inspired us to analyze theoretically the spin dynamics in tubular conductors. We have used a cylindrical InAs nanowire with a surface 2DEG as a model system, but our findings also apply to other systems, for example, InN or InSb nanowires.…”