Abstract
A comparative study of the radiation-induced magnetoresistance oscillations in the high mobility GaAs/AlGaAs heterostructure two dimensional electron system (2DES) under linearly- and circularly- polarized microwave excitation indicates a profound difference in the response observed upon rotating the microwave launcher for the two cases, although circularly polarized microwave radiation induced magnetoresistance oscillations observed at low magnetic fields are similar to the oscillations observed with linearly polarized radiation. For the linearly polarized radiation, the magnetoresistive response is a strong sinusoidal function of the launcher rotation (or linear polarization) angle, θ. For circularly polarized radiation, the oscillatory magnetoresistive response is hardly sensitive to θ.
Highlights
The role of the polarization angle in experiments that utilize linearly polarized microwave photo-excitation has been a topic of interest in recent work[6,7,57,58]
This study has compared the magnetoresistive response of the high mobility GaAs/AlGaAs 2D electron system under linearly- and circularly- polarized microwave photo-excitation in the frequency band spanning 43 ≤ f ≤ 5 0 GHz
The results show that (a) peaks and valleys in the radiation-induced oscillatory magnetoresistance shift to higher magnetic field with an increase in the microwave frequency for circularly polarized radiation, similar to the response for linearly polarized radiation. (b) The amplitude of the radiation-induced oscillatory magnetoresistance increases non-linearly with the microwave power for circularly polarized radiation, similar to the observed response for linearly polarized microwaves. (c)
Summary
The role of the polarization angle in experiments that utilize linearly polarized microwave photo-excitation has been a topic of interest in recent work[6,7,57,58]. As circularly polarized microwave photo-excitation is concerned, an experimental study[19] examining the magnetotransport response for circular polarization reported on the immunity of the radiation-induced magnetoresistance oscillations to the polarization orientation for both circularly polarized and linearly polarized radiation. Lei and Liu examined radiation-induced magnetoresistance oscillations under a variety of polarization conditions, including linearly polarized microwaves with different polarization directions, and circularly polarized microwaves with left handed and right handed orientations[45,59]. They found that the amplitude of the magnetoresistance oscillations differs with the type of polarization of the radiation. Nearly similar response is observed in the cyclotron resonance activeand inactive- conditions for the circularly polarized radiation at the examined frequencies
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