Current-voltage characteristics and the zero-resistance state in a 2DEG

TL;DR

This paper investigates the current-voltage behavior of a 2D electron gas under microwave irradiation and magnetic fields, revealing how geometry influences observed negative conductance and the emergence of zero-resistance states.

Contribution

It demonstrates that the CVC shape depends on experimental setup due to the Hall effect, clarifying the nature of zero-resistance states in 2DEG systems.

Findings

CVC shape depends on geometry (Hall bar vs. Corbino)

Negative differential conductivity leads to zero-resistance or zero-conductance states

Instabilities cause domain formations affecting observed states

Abstract

We study the current-voltage characteristics (CVC) of two-dimensional electron gases (2DEG) with microwave induced negative conductance in a magnetic field. We show that due to the Hall effect, strictly speaking there is no distinction between N- and S-shaped CVCs. Instead the observed CVC depends on the experimental setup with, e.g., an N-shaped CVC in a Corbino disc geometry corresponding to an S-shaped CVC in a Hall bar geometry in a strong magnetic field. We argue that instabilities of homogeneous states in regions of negative differential conductivity lead to the observation of zero resistance in Hall bars and zero conductance in Corbino discs and we discuss the structure of current and electric field domains.