Quantum Hall Effect in Ultrahigh Mobility Two-dimensional Hole Gas of Black Phosphorus

TL;DR

This study demonstrates the observation of quantum Hall effect in ultrahigh mobility black phosphorus heterostructures, revealing detailed electronic properties and spin-related phenomena at cryogenic temperatures.

Contribution

It reports the first observation of quantum Hall effect in black phosphorus with record-high mobility and detailed measurements of effective mass and g-factor.

Findings

Room temperature mobility of 5200 cm^2/Vs limited by phonons

Cryogenic mobility reaching 45,000 cm^2/Vs

Quantum Hall effect observed with Landau levels down to v=2

Abstract

We demonstrate that a field effect transistor (FET) made of few layer black phosphorus (BP) encapsulated in hexagonal boron nitride (h-BN) in vacuum, exhibts the room temperature hole mobility of 5200 $cm^2/Vs$ being limited just by the phonon scattering. At cryogenic tempeature the FET mobility increases up to 45,000 $cm^2/Vs$, which is eight times higher compared with the mobility obtained in earlier reports. The unprecedentedly clean h-BN/BP/h-BN heterostructure exhibits Shubnikov-de Haas oscillations and quantum Hall effect with Landau level (LL) filling factors down to v=2 in conventional laboratory magnetic fields. Moreover, carrier density independent effective mass m=0.26 m_0 is measured, and Lande g-factor g=2.47 is reported. Furthermore, an indication for a distinct hole transport behavior with up and down spin orientation is found.