Spin density waves in periodically strained graphene nanoribbons

Abstract

Zigzag graphene nanoribbons (ZGNRs) are antiferromagnetic in the ground state with zero net magnetization due to the compensation of contributions from opposite edges. Uniform deformations (both shear and axial) do not produce magnetization due to symmetry restrictions. However, we report the results of first-principles calculations that predict the induction of spin density waves (SDWs) in ZGNRs under non-uniform periodic strain. Using the density functional theory (DFT) method, we show that a sinusoidal magnetization variation along the axis of the ribbon occurs under a sinusoidal transversal shear strain. SDWs appear due to the presence of a strain gradient that induced asymmetry of magnetization on opposite edges of ZGNRs which do not compensate each other. The amplitude of SDWs is estimated at $0.066m B when deformations transverse to the ZGNR axis have a sinusoidal profile with a period of 88.6Å and an amplitude of 1Å. Our study suggests that the periodic lattice deformations strongly affect the magnetic structure of ZGNRs in the case of acoustic phonons or mechanical waves.

Excited spin density waves in zigzag graphene nanoribbons

“…The investigation is limited to the model system and simple excitation modes; the spin polarization distribution has seldom been seen. We also notice that someone proposed that there exist spin density waves in the periodically strained GNR by the first principle calculations [22]. On the experiment aspect, G.Z.…”

“…Recently Hagymasi et al use the density-matrix renormalization-group algorithm to study some excitations in zigzag GNR [23]. We also notice that some spin density wave (SDW) has been proposed in a zigzag GNR, which is induced by a periodically shear strain on the GNR [24].…”

Graphene nanoribbons under axial compressive and point tensile stresses

“…In addition, the spin polarized first principle calculations have shown that zigzag GNRs are magnetic in nature, whereas armchair GNRs show non-magnetic behaviour [54]. When the strain is applied to the magnetic GNRs, magnetic moment is induced along zigzag edges with sinusoidal deformations [55].…”

Twisted helical armchair graphene nanoribbons: mechanical and electronic properties

“…In principle, by suitable engineering of local strain profiles, all-graphene electronics can be integrated on a single graphene sheet. The various ways to apply inplane strain in graphene nanoribbons (GNRs) including tensile strain [1,2], bending [3,4], and intrinsic rippling [5] can be used to develop materials with tunable properties. Nevertheless, the off-plane, for example, twisting [6], can offer another way to exploit the core and edge region interaction of GNRs.…”