Magnetointersubband resistance oscillations in GaAs quantum wells placed in a tilted magnetic field

Abstract

The magnetotransport of highly mobile 2D electrons in wide GaAs single quantum wells with three populated subbands placed in titled magnetic fields is studied. The bottoms of the lower two subbands have nearly the same energy while the bottom of the third subband has a much higher energy (E1 ≈ E2 << E3). At zero in-plane magnetic fields magneto-intersubband oscillations (MISO) between the i th and j th subbands are observed and obey the relation ∆ij = Ej −Ei = k·hωc, where ωc is the cyclotron frequency and k is an integer. An application of in-plane magnetic field produces dramatic changes in MISO and the corresponding electron spectrum. Three regimes are identified. Athωc ≪ ∆12 the in-plane magnetic field increases considerably the gap ∆12, which is consistent with the semi-classical regime of electron propagation. In contrast at strong magnetic fieldshωc ≫ ∆12 relatively weak oscillating variations of the electron spectrum with the in-plane magnetic field are observed. Athωc ≈ ∆12 the electron spectrum undergoes a transition between these two regimes through magnetic breakdown. In this transition regime MISO with odd quantum number k terminate, while MISO corresponding to even k evolve continuously into the high field regime corresponding tohωc ≫ ∆12.

Quantum electron transport in magnetically entangled subbands

“…Indeed, due to in-plane magnetic field each level of a subband interacts directly with two levels of another subband leading to an entangled mesh of the couplings between quantum levels. 15 No effects of electron spin degree of freedom were detected in this study.…”

“…In figure 5(a) solid lines present dependence of normalized QPMR on reciprocal magnetic field, 1/B ⊥ , at different angles α between the direction of the magnetic field and the normal to the sample. Similar to the case of the quantum wells with a single populated subband 15 QPMR is obtained by a subtraction of the magnetoresistance at the critical angle α c corresponding to the condition ∆ Z /hω c =1/2 15,38 . At this condition quantum levels are equally separated byhω c /2 and the fundamental harmonic of DOS is absent.…”

“…The observed overall increase of the quantum scattering times approximately by a factor of two correlates with the decrease of the density of state by about two times due to the spin splitting of separated Landau levels, that leads to the proportional reduction of the quantum scattering rate. 15 …”

“…The proposed model utilizes a similarity of QPMR and MagnetoInterSubband (MISO) resistance oscillations. 5,6,[13][14][15] The model considers two spin subbands shifted with respect to each other by Zeeman effect. In each spin subband the energy spectrum evolves in accordance with Landau quantization.…”

“…15 An application of in-plane magnetic field produces dramatic changes in MISO and the corresponding electron spectrum. Three regimes have been identified.…”