Saturation of phase coherence length in GaAs/AlGaAs on-facet quantum wires

Abstract

Phase coherence length Lφ of on-facet quantum wires is determined at temperatures down to 50 mK by three methods: magnetoresistance, conductance fluctuation amplitude, and the conductance fluctuation correlation field. It is found that Lφ saturates below about 0.4 K. This saturation is identified as due to spin-orbit interaction, which has no temperature dependence. This result is supported by positive magnetoresistance under a weak magnetic field.

Saturation of electron phase breaking time in GaAs/AlGaAs quantum wires

“…for the samples made by FIB implantation appears to be dependent on /E F and, therefore, the spin-orbit scattering might be one possibility for the origins of the saturation for a relatively low-mobility and highelectron-denity quantum wire. 9 However, we have never ob-served antilocalization signals due to spin-orbit scattering at low magnetic fields.…”

“…12 For simplicity, we have tried magnetoconductance fitting in a condition that so ӷ i and s ӷ i ; the former condition is tentatively reasonable, since we have never observed antilocalization characteristic to the spin-orbit interaction. 9 On the other hand, a profile of magnetoconductance with s is nearly identical to that without s for a shorter i . The influence of s will be discussed in Sec.…”

“…Ikoma and Hiramoto, however, found that saturates below 3 K in a quantum wire made by focused ion beam ͑FIB͒ implantation, even when the saturated l is much shorter than the wire length. 7 On the other hand, Bird et al, Fukai et al, and Taylor et al also found saturation and they ascribed the saturation to a lack of diffusion motion, 8 to spin-orbit interaction, 9 and to the surface scattering process, 10 respectively. These studies have been studied by using only a few quantum wires with a small range of parameters of Fermi energy, mobility, as well as temperature.…”

Quantum Effect Physics, Electronics and Applications: Proceedings of the International Workshop Held in Luxor, Egypt on January 6-10, 1992

“…This saturation is also reported by other authors ). The spin-orbit scattering is a possible cause as Fukai et al (1990) proposed. The spin-orbit scattering should induce positive magnetoresistance at low magnetic field as Kawaguchi et al (1987) reported in an InAs invcrsion layer.…”

Low-temperature saturation of phase coherence length in topological insulators

“…Although theoretically, all these mechanisms lead to a diverging l φ with decreasing T [6,7,13,14], experimentally, the increase of l φ with reducing T is often followed by its saturation for T ≤ 2 − 5 K [11,12,15,16]. The saturation of l φ at a finite value instead of its divergence for T → 0 K, which is predicted for electron-electron or electron-phonon interactions, has been a matter of active discourse [14,[17][18][19][20][21][22][23][24][25][26][27][28].In this report, we have inspected the factors that can lead to the saturation of l φ in TIs by measuring both gate-voltage (V G ) and time (t)-dependent conductance fluctuations and magneto-resistance (MR) [27,[29][30][31][32][33][34][35][36]. Conductance fluctuations result from the quantum interference of different electron trajectories, manifested as sample specific, aperiodic fluctuations in the conductance due to varying disorder configuration, Fermi energy, and magnetic field; such fluctuations have been used as a tool to probe the presence of time-reversal symmetry (TRS) breaking disorders, since the saturation of l φ at low T is often attributed to spin-flip scattering processes.…”