Effective magnetic correlations in hole-doped graphene nanoflakes

TL;DR

This study explores how hole doping affects magnetic correlations in zig-zag graphene nanoflakes, revealing potential for electrostatically controlled spintronic applications through magnetic state switching.

Contribution

It demonstrates that hole doping induces a transition from antiferromagnetic to ferromagnetic correlations, enabling control over magnetic states in graphene nanoflakes.

Findings

Doped holes delocalize near edges, mediating ferromagnetic correlations.

Magnetic transition exhibits hysteresis, indicating coexistence of states.

Hole doping can switch magnetic states, useful for spintronics.

Abstract

The magnetic properties of zig-zag graphene nanoflakes (ZGNF) are investigated within the framework of the dynamical mean-field theory. At half-filling and for realistic values of the local interaction, the ZGNF is in a fully compensated antiferromagnetic (AF) state, which is found to be robust against temperature fluctuations. Introducing charge carriers in the AF background drives the ZGNF metallic and stabilizes a magnetic state with a net uncompensated moment at low temperature. The change in magnetism is ascribed to the delocalization of the doped holes in the proximity of the edges, which mediate ferromagnetic correlations between the localized magnetic moments. Depending on the hole concentration, the magnetic transition may display a pronounced hysteresis over a wide range of temperature, indicating the coexistence of magnetic states with different symmetry. This suggests the possibility of achieving the electrostatic control of the magnetic state of ZGNFs to realize a switchable spintronic device.