Microwave Reflection From The Microwave Photo-Excited High Mobility GaAs/AlGaAs Two-Dimensional Electron System
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Microwave Reflection From The Microwave Photo-Excited High Mobility GaAs/AlGaAs Two-Dimensional Electron System Tianyu Ye1, R. G. Mani1 and W. Wegscheider2 1
Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303, USA.
2
Laboratorium fur Festkorperphysik, ETH-Zurich, 8093 Zurich, Switzerland.
ABSTRACT We examine the microwave reflection from the high mobility GaAs/AlGaAs twodimensional electron system (2DES). Strong correlations have been observed between the microwave induced magnetoresistance oscillations and the microwave reflection oscillations in a concurrent measurement of the microwave illuminated magnetoresistance and the microwave reflection from the 2DES. The correlations were followed as a function of the microwave frequency and the microwave power dependent. Different existing theories are considered to explain the results. INTRODUCTION Zero-resistance states have been a topic of interest in the two dimensional electron system (2DES) for the past several decades. It is well known that the 2DES exhibits quantum Hall effect when it is subjected to low temperature and strong perpendicular magnetic fields. Studies of QHE show that a 2DES with well-separated Landau levels periodically exhibits zero resistance states. More recently, a special type of zero resistance state – the microwave induced zero resistance state (MIZRS) - was discovered [1]. Here, a high mobility 2DES subjected to low temperature, a perpendicular magnetic field, and microwave illumination shows a magnetoresistance that periodically exhibit zero resistance states in the vicinity of B-1= [4/(4j+1)]-1(2πfm*/e)-1, where B is the magnetic field, f is the microwave frequency, e is the electron charge, and m* is the electron effective mass. In a lower mobility sample and with smaller microwave power, MIZRS turn into the minima of microwave induced magnetoresistance oscillations (MIMOs) [1, 2]. In principle, such strong microwave response could have potential application in gigahertz and terahertz electronics. Theoretically, MIZRS and MIMOs could be understood by: impurity assisted inter- and intra- Landau levels transition made by microwave illumination (displacement model) [3, 4], microwave induced oscillating electron distribution (inelastic model) [5] and microwave driven oscillating electron orbit (electron orbit model) [6]. Since their discovery, MIZRS and MIMOs have attracted a lot of research interest. Some research focus on the direct measurement of electric signal in 2DES itself while changing external parameters [7-15], such as microwave frequency, power or polarization, even samples’ quality. Others focus on measuring microwave wave absorption, reflection and transmission [1619] from 2DES and their correlation with MIMOs. Although such measurements are indirect measurement from 2DES, they could clearly reveal physical contributions of MIMOs and MIZRS, and identify the relative contributions of suggested theoretical mechanisms.
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Here, we examine the microwave reflection from high mobility 2DES an
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