Pressure-induced Lifshitz transition in black phosphorus

TL;DR

Applying moderate pressure to black phosphorus induces a Lifshitz transition from semiconductor to semimetal, revealing complex Fermi surface topology and Dirac-like fermions, which could enable new electronic states and applications.

Contribution

Demonstrates pressure-induced Lifshitz transition in black phosphorus, revealing emergent Dirac fermions and complex Fermi surface topology, expanding its potential for novel electronic states.

Findings

Lifshitz transition from semiconductor to semimetal at ~1.2 GPa

Colossal magnetoresistance observed in the semimetallic phase

Emergence of Dirac-like fermions under pressure

Abstract

In a semimetal, both electron and hole carriers contribute to the density of states at the Fermi level. The small band overlaps and multi-band effects give rise to many novel electronic properties, such as relativistic Dirac fermions with linear dispersion, titanic magnetoresistance and unconventional superconductivity. Black phosphorus has recently emerged as an exceptional semiconductor with high carrier mobility and a direct, tunable bandgap. Of particular importance is the search for exotic electronic states in black phosphorus, which may amplify the material's potential beyond semiconductor devices. Here we show that a moderate hydrostatic pressure effectively suppresses the band gap and induces a Lifshitz transition from semiconductor to semimetal in black phosphorus; a colossal magnetoresistance is observed in the semimetallic phase. Quantum oscillations in high magnetic field reveal the complex Fermi surface topology of the semimetallic black phosphorus. In particular, a Dirac-like fermion emerges at around 1.2 GPa, which is continuously tuned by external pressure. The observed semi-metallic behavior greatly enriches black phosphorus's material property, and sets the stage for the exploration of novel electronic states in this material. Moreover, these interesting behaviors make phosphorene a good candidate for the realization of a new two-dimensional relativistic electron system, other than graphene.