# Quantum Transport in Ambipolar Few-layer Black Phosphorus

## TL;DR

This paper demonstrates ambipolar quantum transport in few-layer black phosphorus, revealing quantum Hall effects for both holes and electrons, and measures spin susceptibility, highlighting its potential for quantum spintronics applications.

## Contribution

It reports the first observation of ambipolar quantum Hall effects in few-layer black phosphorus and provides quantitative spin susceptibility measurements for electron-doped samples.

## Key findings

- Quantum Hall effect observed for both hole and electron transport.
- Spin susceptibility for electron-doped black phosphorus measured as 1.1.
- Electron-doped black phosphorus shows an equidistant spin-resolved Landau level structure.

## Abstract

Few-layer black phosphorus possesses unique electronic properties giving rise to distinct quantum phenomena and thus offers a fertile platform to explore the emergent correlation phenomena in low dimensions. A great progress has been demonstrated in improving the quality of hole-doped few-layer black phosphorus and its quantum transport studies, whereas the same achievements are rather modest for electron-doped few-layer black phosphorus. Here, we report the ambipolar quantum transport in few-layer black phosphorus exhibiting undoubtedly the quantum Hall effect for hole transport and showing clear signatures of the quantum Hall effect for electron transport. By bringing the spin-resolved Landau levels of the electron-doped black phosphorus to the coincidence, we measure the spin susceptibility $\chi_s=m^\ast g^\ast=1.1\pm0.03$. This value is larger than for hole-doped black phosphorus and illustrates an energetically equidistant arrangement of spin-resolved Landau levels. Evidently, the n-type black phosphorus offers a unique platform with equidistant sequence of spin-up and spin-down states for exploring the quantum spintronic.