2D Lattice of coupled Sinai billiards: metal or insulator at g<<1

TL;DR

This study examines a 2D lattice of coupled Sinai billiards in a high-mobility electron gas, revealing metallic behavior at low reduced conductivity g<<1, contrary to expectations of Anderson localization.

Contribution

It provides experimental evidence that a 2D Sinai billiard lattice remains metallic at g<<1, challenging the conventional localization theory.

Findings

Weak temperature dependence of g at g<<1

Large negative magnetoresistance with Lorentz line-shape

Persistence of Shubnikov-de Haas oscillations at g<<1

Abstract

We investigate the transport in a two-dimensional (2D) lattice of coupled Sinai billiards fabricated on the basis of a high-mobility 2D electron gas in GaAs/AlGaAs heterojunction. For the states with low reduced conductivity g<<1 an anomalously weak temperature dependence of g was found. The large negative magnetoresistance described by the Lorentz line-shape of the width corresponding to the half magnetic flux quantum through the area of the billiard is observed. In going from g>1 to g<<1 it strongly increases. The Shubnikov-de Haas oscillations and commensurability magnetoresistance peak are preserved at g<<1. The data suggest that the system studied behaves more like a metal than an insulator at g<<1 and is not described by the generally accepted picture of Anderson localization.