Magnetoplasmon resonance in a two-dimensional electron system driven into a zero-resistance state

We report on a very strong, and a rather sharp, photoresistance peak originating from a dimensional magnetoplasmon resonance (MPR) in a high-mobility GaAs/AlGaAs quantum well driven by microwave radiation into a zero-resistance state (ZRS). The analysis of the MPR signal reveals a negative background, providing experimental evidence for the concept of absolute negative resistance associated with the ZRS. When the system is further subject to a dc field, the maxima of microwave-induced resistance oscillations decay away and the system reveals a state with close-to-zero differential resistance. The MPR peak, on the other hand, remains essentially unchanged, indicating robust Ohmic behavior under the MPR conditions.

Figure 1

Magnetoresistivity ${\rho }_{\omega }\left(B\right)$ (Ref. 43) (dark curves) under microwave irradiation of frequency (a) $f=170$ GHz and (b) $f=150$ GHz at $T=0.65$ K. Both panels also show $\rho \left(B\right)$ measured without irradiation (light curves). The dashed curves are fits to the data (see text). The vertical lines are drawn at the harmonics of the cyclotron resonance, $\omega /{\omega }_c=1,2,3,...,$ obtained from the MIRO period. The MPR and ${\mathcal{X}}_2$ peaks are marked by “MPR” and by “${\mathcal{X}}_2$,” respectively. Arrows mark an additional series of peaks.

Figure 2

Differential resistivity $r_{\omega }$ vs magnetic field $B$ under microwave irradiation of $f=165$ GHz measured at $T=1.4$ K for different current densities from $j=0$ to 0.20 A/m, in a step of 0.05 A/m. The traces are vertically offset for clarity by 2.5 $\Omega$. The vertical lines are drawn at the harmonics of the cyclotron resonance, $\omega /{\omega }_c=1,2,3,\cdots .$