Microwave induced negative resistance states in 2D electron gas with periodic modulation

TL;DR

This paper investigates microwave-induced negative resistance states in a 2D electron gas with periodic modulation, revealing oscillations and conditions for negative resistance that depend on electron mobility, microwave power, and lattice parameters.

Contribution

The study provides a theoretical analysis of negative resistance states in modulated 2DES under microwave irradiation, incorporating Landau and microwave effects exactly and treating the periodic potential perturbatively.

Findings

Negative resistance states emerge at high mobility and microwave power.

Oscillations in resistivity are periodic in the ratio of microwave frequency to cyclotron frequency.

Negative resistance occurs within a narrow lattice parameter window around the magnetic length.

Abstract

We study the microwave-induced photoconductivity of a two-dimensional electron system (2DES) in the presence of a magnetic field and a two-dimensional modulation. The microwave and Landau contributions are exactly taken into account, while the periodic potential is treated perturbatively. The longitudinal resistivity exhibits oscillations, periodic in $\omega / \omega_c$. Negative resistance states (NRS) develop for sufficiently high electron mobility and microwave power. This phenomenon appears in a narrow window region of values of the lattice parameter ($a$), around $a \sim l_B$, where $l_B$ is the magnetic length. It is proposed that these phenomena may be observed in artificially fabricated arrays of periodic scatterers at the interface of ultraclean heterostructures. {73.20.At,05.60.-k, 72.15.Rn}