Cyclotron resonance in the extreme quantum limit

Abstract

We have studied the cyclotron resonance (CR) of high mobility 2D electrons in GaAs/AlGaAs heterostructures at 2.3 ≤ T≤4.2 K, using far infrared lasers with wavelengths ranged from 96.52 to 512.88 μm. The CR experiments are carried out in the low density range, 1 × 10 10 ≲ n s ≤1.2 × 10 11 cm −2, which is controlled by using either a back gate or a front gate. Using back gate. Using back gate, the effective mass is constant after the nonparabolicity correction and the CR lines are extremely narrow. The extracted CR lifetime, τ CR , depends on n s following τ CR ∝ n s 1.9 ± 0.1 in the extreme quantum limit, 0.08 < v < 0.4. On the other hand, when a front gate is used, the CR lines show strong inhomogeneous broadening, which can be explained by assuming that { 30% of 2D area is not affected by the gate voltage.