Angular magnetoresistance oscillations in bilayers in tilted magnetic fields

Abstract

Angular magnetoresistance oscillations (AMRO) were originally discovered in organic conductors and then found in many other layered metals. It should be possible to observe AMRO to semiconducting bilayers as well. Here we present an intuitive geometrical interpretation of AMRO as the Aharonov-Bohm interference effect, both in real and momentum spaces, for balanced and imbalanced bilayers. Applications to the experiments with bilayers in tilted magnetic fields in the metallic state are discussed. We speculate that AMRO may be also observed when each layer of the bilayer is in the composite-fermion state.

Interlayer interference in double wells in a tilted magnetic field

“…Using these parameters, we obtained the distance between wave-function maxima d = 170-180 Å for d b = 14 Å barrier sample, which roughly agrees with the expected value ͑see Table I͒. In the last part we reproduce the intuitive geometrical interpretation of the observed oscillatory effects as a manifestation of the Aharonov-Bohm effect in the titled magnetic field, first presented in Ref. 9. Figure 8͑a͒ shows schematically two layers separated by the distance d in a tilted magnetic field.…”

“…8͑b͒, produces the phase shift between cyclotron orbits in different layers, which leads to the oscillations of the effective interlayer tunneling amplitude. 9 In momentum space in-plane magnetic field introduces the shift of the two Fermi surfaces ⌬k ʈ = eB ʈ d / ប relative to each other, 20 as shown in Fig. 1͑c͒.…”

“…1 The AB effect has been observed in lithographically defined diffusive metallic and semiconductor rings, 2,3 ballistic semiconductor rings, 4,5 carbon nanotubes, 6 and self-assembled quantum rings. 7 Recently oscillatory phenomena in quasi-one-dimensional organic semiconductor 8 and semiconductor bilayers 9 have been analyzed and interpreted as the AB effect, both in the real and momentum spaces.…”

“…It is worth noting that AMRO in organic conductors has been studied for high filling factors, and the relationship between semiconductor bilayers and other layered materials was demonstrated only recently in a theoretical paper. 9 Due to a high mobility, the double quantum wells allow the studying of AMRO in both regimes: for small filling factors, when the quantum Hall effect is well resolved, and for high filling factors, when quasiclassical approximation is valid.…”

Sensitivity of the interlayer magnetoresistance of layered metals to intralayer anisotropies

“…16 AMROs are essentially a geometric resonance involving the cyclotron orbits projected onto the plane parallel to the layers. 17 In this sense, they are similar to geometric commensurability oscillations in magnetoresistance seen for two-dimensional electron gases in semiconductor heterostructures. [18][19][20] In this paper, we present the following results for interlayer magnetotransport in a layered Fermi liquid metal.…”