Ultrasonic approach to the integer and fractional quantum Hall effect

Oscillating Sign of Drag in High Landau Levels

“…In passing, we note that while the sign changes of Γ(q, ω) with qR c in the ballistic limit seem to have only minor consequences for drag, they should be observable in other experiments of recent interest, namely in pumping [15] and in acoustoelectric experiments [9], which also measure the rectification coefficient Γ(q, ω) [16]. In pumping experiments, a potential φ(r, t) is applied to the system which is typically made up of the sum of two potentials oscillating out of phase φ(r, t) = φ 1 (r) cos(ωt) + φ 2 (r) cos(ωt + δ).…”

“…We note that the acoustoelectric experiments of Ref. [9], which were carried out in the diffusive regime, have been successfully analysed using Eq. (6).…”

Surface acoustic wave-induced electroluminescence intensity oscillation in planar light-emitting devices

“…SAWs propagating through mesas containing highquality 2DEGs indeed drive modifications on the 2DEG equilibrium state. Acoustic waves propagating along piezo-electric substrates are accompanied by potential waves which can trap electrons in their minima and induce dc currents or voltages [5,6,7]. The discovery of the so-called acoustoelectric effect was followed by the proposal of innovative device concepts.…”

Surface acoustic wave-driven planar light-emitting device

“…Lattice deformations induced by SAWs propagating on a piezoelectric substrate (i. e. GaAs) are accompanied by potential waves which interact with charge carriers confined in the heterostructure leading to energy and momentum transfer. This interaction can drag carriers along the SAW-propagation direction resulting in a net DC current or voltage, the acoustoelectric effect [2,3,4]. Moreover, this same interaction induces changes in SAW velocity and amplitude that can be used to probe 2DSs transport properties [5,6,7,8].…”