In-plane anisotropic transport in the 2DEG with a strong spin–orbit coupling in In0.75Ga0.25As/In0.75Al0.25As hetero-junctions

Dephasing Measurements in InGaAs/AlInAs Heterostructures: Manifestations of Spin-Orbit and Zeeman Interactions

“…Here we focus on nanostructures in which the electrons are subjected to significant spin-orbit coupling, and report on studies of weak antilocalization (WAL) effects, universal conductance fluctuations (UCF), and Aharonov-Bohm (AB) oscillations in the magnetoresistance data of mesoscopic samples of InGaAs/AlInAs. This material is well-known for its strong Rashba-type spin-orbit interaction, 12,13 characterized by the coupling strength α so of about of 10 −11 eV m. 14,15 This value corresponds to a spin-orbit energy 16 ω so = (m * v F / )α so ≈ 1.6 meV (the Fermi wave vector of our samples is ≈ 1.58 × 10 6 cm −1 ). The Landé factor of our material is about 15, and hence the Zeeman energy is ω Z ≈ 0.87×B meV, where the magnetic field B is measured in Tesla.…”

“…This material is wellknown for its strong Rashba-type spin-orbit interaction [12] [13], characterized by the coupling strength so α of about of 10 −11 eV m [14] [15]. This value corresponds to a spin-orbit energy [16] ( ) The spin-orbit interaction, coupling the momentum of the electron to its spin, in conjunction with a Zeeman field gives rise to Berry phases [17].…”

High-In-content InGaAs quantum point contacts fabricated using focused ion beam system equipped with N2gas field ion source

“…In this study, we employed N 2 GFIS-FIB to form QPCs in an inverted high-In-content InGaAs MDH 20,21) by physical sputtering. To control QPCs electrically, we formed top-gate structures by atomic layer deposition (ALD) of Al 2 O 3 followed by Ti/Au evaporation and lift-off after GFIS-FIB fine patterning.…”

“…The inverted high-In-content InGaAs MDH was grown on a semi-insulating GaAs(001) substrate by molecular beam epitaxy with InAlAs step-graded buffers (SGBs). 20,21) The MDH consists of a 60-nm-thick InGaAs channel (top), a 20-nm-thick InAlAs spacer, a Si delta-doping layer, a 200-nmthick InAlAs barrier, and InAlAs SGBs (bottom). The nominal In content is 0.75 for active layers (channel, spacer, and barrier).…”

“…However, the half-integer quantized conductance (0.5 © 2e 2 /h = e 2 /h), which is expected to appear in the case of strong SOC, 7,10,12) could not be observed. Since similar InGaAs MDHs experimentally show strong Rashba SOC (³10 ¹11 -10 ¹12 eVm), [20][21][22] ionized N 2 beam irradiation during imaging and/or sputtering in the GFIS-FIB process may reduce the sheet electron concentration locally and weaken the SOC owing to the reduction in effective electric field. Also, the conductance seems saturated less than twice the quantized conductance (2 © 2e 2 /h).…”