Magnetoelectric effect in functionalized few-layer graphene

Abstract

We show that the spin moment induced by sp 3 -type defects created by different covalent functionalizations on a few-layer graphene structure can be controlled by an external electric field. Based on ab initio density functional calculations, including van der Waals interactions, we find that this effect has dependence on the number of stacked layers, concentration of point defects but the interplay of both with the electric field drives the system to a half-metallic state. The calculated magnetoelectric coefficient α has value comparable to those found for ferromagnetic thin films (e.g. Fe, Co, Ni) and magnetoelectric surfaces (e.g. CrO2). The value of α also agrees with the universal value predicted for ferromagnetic half-metals and also points to a novel route to induce half-metallicity in graphene using surface decoration.

Momentum-Space Entanglement Spectrum of Bosons and Fermions with Interactions

“…For example, the entanglement entropy (EE) is given by Tr(ρ A lnρ A ) = Tr(ρ B lnρ B ). The entanglement spectrum (ES) [2] (defined as the set of eigenvalues of a fictitious entanglement Hamiltonian, H e , with ρ A written as e −H e ) is a useful tool in understanding topological states of matter and strongly correlated systems, including fractional quantum Hall (FQH) systems [2-10], quantum spin chains [11][12][13][14][15][16][17] and ladders [18][19][20][21][22][23][24][25][26], topological insulators [27][28][29][30][31][32], symmetry broken phases [33,34], and other systems in one [35][36][37][38][39] and two [40][41][42][43][44][45][46][47][48][49][50][51][52] spatial dimensions. These studies predominantly focused on real / orbital space entanglement.…”

The extraordinary magnetoelectric response in silicene doped with Fe and Cr atoms

“…For Fe-II, there exists a sharp switching of magnetism which is different from completely linear ME effect of graphene or functionalized graphene. [11][12][13][14][15][16] The magnetic moment increases nearly linearly above the electric field of À0.6 V/Å . When the electric field strength is below À0.6 V/Å , the magnetic moment jumps to zero as shown in Fig.…”

“…11,12 There exists the ME effect in functionalized multilayer graphene. 13,14 The graphene nanoflakes on substrates show a nonlinear-linear transition of the ME effect. 15 In addition, the magnetism of the adatoms on graphene can be tuned by external electric field.…”

“…1,9,10 With the booming nanomaterials, some studies on the magnetic modulation of the carbon-based nanomaterials by external electric field have been proposed. [11][12][13][14][15][16][17][18] For instance, the linear ME effect can be tuned in graphene nanoribbons on Si substrates by a bias voltage. 11,12 There exists the ME effect in functionalized multilayer graphene.…”

Coulomb excitations of monolayer germanene

“…Many theoretical predictions are made on few-layer graphenes1640414243444546474849, but only some studies on mono-layer silicene and germanene. The low-frequency plasmons due to free carriers in conduction and/or valence bands can be generated by the temperature404142, interlayer atomic interactions434445, doping464748, magnetic field42, and electric field4445.…”