Quantum Hall Effect in Black Phosphorus Two-dimensional Electron Gas

TL;DR

This paper reports the first observation of the integer quantum Hall effect in high mobility black phosphorus 2DEG, achieved through a van der Waals heterostructure, revealing insights into Landau level energetics and enabling future quantum transport studies.

Contribution

The study demonstrates the realization of high quality black phosphorus 2DEG with mobility up to 6000 cm²V⁻¹s⁻¹ and the first observation of the quantum Hall effect in this material.

Findings

Quantum Hall effect observed in black phosphorus 2DEG

Carrier Hall mobility reached 6000 cm²V⁻¹s⁻¹

Insights into spin-split Landau levels obtained

Abstract

Development of new, high quality functional materials has been at the forefront of condensed matter research. The recent advent of two-dimensional black phosphorus has greatly enriched the material base of two-dimensional electron systems. Significant progress has been made to achieve high mobility black phosphorus two-dimensional electron gas (2DEG) since the development of the first black phosphorus field-effect transistors (FETs)$^{1-4}$. Here, we reach a milestone in developing high quality black phosphorus 2DEG - the observation of integer quantum Hall (QH) effect. We achieve high quality by embedding the black phosphorus 2DEG in a van der Waals heterostructure close to a graphite back gate; the graphite gate screens the impurity potential in the 2DEG, and brings the carrier Hall mobility up to 6000 $cm^{2}V^{-1}s^{-1}$. The exceptional mobility enabled us, for the first time, to observe QH effect, and to gain important information on the energetics of the spin-split Landau levels in black phosphorus. Our results set the stage for further study on quantum transport and device application in the ultrahigh mobility regime.