Ferrimagnetic and antiferromagnetic phase in bilayer graphene nanoflake controlled with external electric fields

Abstract

The paper presents a computational study of the ground-state magnetic phases of a selected bilayer graphene nanoflake in external electric field and magnetic field. The electric field has parallel and perpendicular component while the magnetic field is oriented in plane. The system consists of two rectangular layers having armchair edges and zigzag terminations with Bernal stacking. The theoretical model is based on a tight binding Hamiltonian with Hubbard term. The magnetic phase diagram involving the total spin is constructed, showing the stability areas of phases with total spin values equal to 0 and 1. A significant stability range of antiferromagnetic, layer-like arrangements is found and extensively discussed. The possibility of switching between nonmagnetic, antiferromagnetic and ferrimagnetic phases with both components of external electric field is demonstrated, being a manifestation of a magnetoelectric effect. The influence of magnetic field on the phase diagrams is analysed.

SPIN-POLARIZED MAGNETO-ELECTRONIC PROPERTIES OF BUCKLED MONOLAYER GaAs

“…The quantized energy spectra and wave functions are computed under the exact diagonalization method. Similar generalized tight-binding model has been widely adopted to make systematic studies on multi-dimensional carbon-based materials and hybrid systems, ranging from three-dimensional (3D) graphites 36,37 , 2D graphenes 36,[38][39][40][41] , 1D graphene nanoribbons (GNRs) [42][43][44][45][46] , carbon nanotubes (CNTs) 47,48 , graphene nanoflake 49 and graphene-related hybrids 50 . It is also suitable for studying the mainstream layered materials, such as group-IV 51 , group-V 52,53 , and TMD 54,55 2D materials.…”

Excitation and phase transitions of spin density waves in graphene nanoribbons

“…From these calculations, we see that the spin stiffness of GNR is dramatically changed in different light intensities. This spin stiffness can also control the dispersion relation of spin waves in many magnetic materials [18].…”

“…Recently, some magnetic correlations or flipped FM state with a domain wall are proposed in the graphene systems [14,15]. Some people also investigated the magnetic phase transitions of the graphene system by this mean-field Hubbard model with some external field [16][17][18].…”

Two-electron conduction band of a graphene quantum dot and coherent spin manipulation

“…The demonstration of spin and valley blockade enables qubit manipulation and readout [32,33]. The experimental synthesis of atomically precise bilayer GQDs remains a great challenge while the electronic properties of such GQDs with well-defined edges have been extensively investigated [34][35][36][37].…”