Vectorial Control of the Spin–Orbit Interaction in Suspended InAs Nanowires

Abstract

Semiconductor nanowires featuring strong spin-orbit interactions (SOI), represent a promising platform for a broad range of novel technologies, such as spintronic applications or topological quantum computation. However, experimental studies into the nature and the orientation of the SOI vector in these wires remain limited despite being of upmost importance. Typical devices feature the nanowires placed on top of a substrate which modifies the SOI vector and spoils the intrinsic symmetries of the system. In this work, we report experimental results on suspended InAs nanowires, in which the wire symmetries are fully preserved and clearly visible in transport measurements. Using a vectorial magnet, the non-trivial evolution of weak anti-localization (WAL) is tracked through all 3D space, and both the spin-orbit length l SO and coherence length l ϕ are determined as a function of the magnetic field magnitude and direction. Studying the angular maps of the WAL signal, we demonstrate that the average SOI within the nanowire is isotropic and that our findings are consistent with a semiclassical quasi-1D model of WAL adapted to include the geometrical constraints of the nanostructure. Moreover, by acting on properly designed side gates, we apply an external electric field introducing an additional vectorial Rashba spin-orbit component whose strength can be controlled by external means. These results give important hints on the intrinsic nature of suspended nanowire and can be interesting for the field of spintronics as well as for the manipulation of Majorana bound states in devices based on hybrid semiconductors.Keywords spin-orbit interaction, nanowire, indium arsenide, weak anti-localization, Rashba effect Over the past decades there has been a growing interest in the study of the spin-orbit interactions in semiconductor systems motivated by the possibility of spintronics applications and quantum computing. 1-5 Systems with strong SOI offer an ideal platform to develop cir-arXiv:1807.04344v2 [cond-mat.mes-hall]

Levitons in helical liquids with Rashba spin-orbit coupling probed by a superconducting contact

“…These Rashba components may be of intrinsic nature or can be induced by means of external electrostatic field, i.e. by acting on lateral gates [97,98]. In addition, a single thin superconducting terminal is coupled to the edge states in the middle of the bar, see Fig.…”

Investigation of InAs–based devices for topological applications

“…[34][35][36][37] To bypass spurious effects, freely suspended nanowires offer a unique platform and are not expected to display any intrinsic electrostatic asymmetry. 28 In this way, one can restore the natural degeneracy of the system, allowing for the investigation of intrinsic properties of spin-orbit interactions. The vectorial dependence of this quantity can be investigated with low-temperature magnetotransport, by tracking the weak anti-localization (WAL) peak 38,39 and measuring the correction to magnetoconductance as a function of bias and magnetic field.…”

“…by averaging the conductance G of a single wire on the different UCF patterns obtained by gating. 28,43,44 In our case, this is achieved by using an AC modulation to the back gate with a low frequency voltage of f = 10.320 Hz and peak-to-peak amplitude V avg bg = 6 V.…”

“…2(a) which shows the conductance correction ∆G(B) = G(B) − G(0) measured at T = 50 mK and at zero gate voltage V SG1 = V SG2 = 0. By comparing the experimental data to the quasi-1D theory of WAL for disordered systems, 28,45,46 a phase coherence length l ϕ ∼ 300 nm and spin-relaxation length l so ∼ 125 nm can be estimated. Since no external electrostatic asymmetry is present in the suspended structure, the observed WAL can be attributed to the internal electric field due to the Fermi level pinning at the NW surface.…”

Self-Organized Conductive Gratings of Au Nanostripe Dimers Enable Tunable Plasmonic Activity

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