Realization of anomalous multiferroicity in free-standing graphene with magnetic adatoms

TL;DR

This paper demonstrates that free-standing graphene with magnetic adatoms can exhibit ferroelectric and multiferroic phases through tuning electronic properties, revealing new ferroic behaviors in a material previously thought non-ferroic.

Contribution

It introduces a method to induce and control multiferroic phases in graphene via magnetic adatoms and electronic tuning, revealing a quantum phase transition.

Findings

Graphene with magnetic adatoms can become ferroelectric and multiferroic.

The multiferroic phase appears abruptly via a quantum phase transition.

Tuning the Dirac cone slope controls ferroic phase transitions.

Abstract

It is generally believed that free-standing graphene does not demonstrate any ferroic properties. In the present work we revise this statement and show that single graphene sheet with a pair of magnetic adatoms can be driven into ferroelectric (FE) and multiferroic (MF) phases by tuning the Dirac cones slope. The transition into the FE phase occurs gradually, but an anomalous MF phase appears abruptly by means of a Quantum Phase Transition. Our findings suggest that such features should exist in graphene recently investigated by Scanning Tunneling Microscopy (Science 352, 437 (2016)).