マイクロ波光励起下における超高移動度GaAs/AlGaAs 2DESの狭負磁気抵抗効果の研究

Study of narrow negative magnetoresistance effect in ultra-high mobility GaAs/AlGaAs 2DES under microwave photo-excitation.

• R L Samaraweera
• B Gunawardana
• T R Nanayakkara
• R C Munasinghe
• A Kriisa
• C Reichl
• W Wegscheider
• R G Mani

抄録

高移動度GaAs/AlGaAs 2DES(≈10cm/Vs)において、ゼロ磁場付近に現れる狭負磁気抵抗効果のマイクロ波誘起変化を、一定の浴温でのマイクロ波入射パワーの関数として実験的に調べた。その結果、マイクロ波強度の増加に伴い、狭い負の磁気抵抗効果が大幅に増大することがわかった。その結果、マイクロ波出力を8mWまで増加させると、特性長が最大50%まで減少することがわかった。また、磁場が存在しない場合の光励起による実効電子温度の変化についても調べた。これらの結果を組み合わせることで、電子の加熱と特性長の変化との間に相関関係があることが示唆された。

The microwave-induced change in the narrow negative magnetoresistance effect that appears around zero magnetic field in high mobility GaAs/AlGaAs 2DES (≈10 cm/Vs) is experimentally examined as a function of incident microwave power at a fixed bath temperature. The experimental results indicate that the narrow negative magnetoresistance effect exhibits substantially increased broadening with increasing microwave intensity. These magnetoresistance data were subjected to lineshape fits to extract possible variation of characteristic lengths with microwave intensity; the results suggest that characteristic lengths decrease by up to 50% upon increasing microwave power up to about 8 mW. We also examine the change in effective electron temperature, T, due to the photo-excitation in the absence of a magnetic field. Combining these results suggests a correlation between electron heating and the observed change in the fit extracted characteristic lengths.