Dirac half-semimetallicity and antiferromagnetism in graphene nanoribbon/hexagonal boron nitride heterojunctions

TL;DR

This paper predicts that graphene nanoribbon/hexagonal boron nitride heterojunctions are half-semimetallic, exhibiting fully spin-polarized Dirac points, and can undergo magnetic phase transitions upon doping, offering potential for spintronic applications.

Contribution

It introduces a novel prediction that specific heterojunctions are half-semimetallic with tunable magnetic properties, advancing the understanding of spin-polarized Dirac fermions in 2D materials.

Findings

Heterojunctions are half-semimetallic with spin-polarized Dirac points.

Charge transfer induces opposite energy shifts at edges while maintaining antiferromagnetism.

Doping causes an antiferromagnetic-to-ferrimagnetic phase transition.

Abstract

Half-metals have been envisioned as active components in spintronic devices by virtue of their completely spin-polarized electrical currents. Actual materials hosting half-metallic phases, however, remain scarce. Here, we predict that recently fabricated heterojunctions of zigzag nanoribbons embedded in two-dimensional hexagonal boron nitride are half-semimetallic, featuring fully spin-polarized Dirac points at the Fermi level. The half-semimetallicity originates from the transfer of charges from hexagonal boron nitride to the embedded graphene nanoribbon. These charges give rise to opposite energy shifts of the states residing at the two edges while preserving their intrinsic antiferromagnetic exchange coupling. Upon doping, an antiferromagnetic-to-ferrimagnetic phase transition occurs in these heterojunctions, with the sign of the excess charge controlling the spatial localization of the net magnetic moments. Our findings demonstrate that such heterojunctions realize tunable one-dimensional conducting channels of spin-polarized Dirac fermions that are seamlessly integrated into a two-dimensional insulator, thus holding promise for the development of carbon-based spintronics.