Strain-induced modulation of exchange interaction in monolayer zigzag nanoribbons of B₂S

Abstract

In this work, the strain modulation of electronic structure and magnetic interaction in monolayer nanoribbons of B2S, a recently realized monolayer system, is investigated. In the first part of our study, we focus on how the electronic structure of monolayer nanoribbons of B2S is modified under uniaxial strains, then employing a tight-binding framework together with the conventional theory of elasticity, we discuss how strain-induced local deformations can be used as a means to affect Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in zigzag nanoribbons of B2S. We show that breaking inversion symmetry in zigzag B2S nanoribbons (ZBSNR), e.g., by introducing staggered sublattice potentials, play a key role in the modulation of their electronic properties. More interestingly, for the ZBSNRs belong to the group M = 4p, with M the width of the ZBSNR and p an integer number, one can see that a band gap, in which a pair of near-midgap bands completely detached from the bulk bands is always observed. As a key feature, the position of the midgap bands in the energy diagram of ZBSNRs can be shifted by applying the in-plane strains εx and εy. Moreover, the near-midgap bandwidth monotonically decreases with increasing strength of the strain and increases with the width of the ZBSNR. The energy gap of the ZBSNRs decreased with increasing the applied strain and ribbon width. The spatial and strain dependency of the exchange interaction in various configurations of the magnetic impurities are also evaluated. It is shown that that magnetic interactions between adsorbed magnetic impurities in B2S nanoribbons can be manipulated by careful strain engineering of such systems. Our results suggest that these tunable electronic and magnetic properties of ZBSNRs mean they may find applications in spintronics and pseudospin electronics based on monolayer B2S nanoribbons. arXiv:1906.11619v1 [cond-mat.mes-hall]

Probing divacancy defects in a zigzag graphene nanoribbon through an RKKY exchange interaction

“…In panels (a), (b) and (c), both the MIs are located on the same edge at positions (5, 1) and (n, 1), with n = 6, 7, 8, ..., and in panels (d), (e) and (f ), both are located inside the zGNR, for a configuration with the first impurity at (5,10) and the second at (n, 10), with n = 6, 7, 8, .... Panels (a) and (e) show a zGNR with one DV at position (150,4); (b) and (f ) represent a zGNR with two DVs at positions (145,4) and (155,4); (c) and (g) refer to a zGNR with 11 DVs at positions (5,4), (34,4), (63,4)...(295, 4) (DV defects with a period of ∆R DV /a = 30), and finally, panels (d) and (h) illustrate a zGNR with 30 DVs at positions (5,4), (15,4), (25,4)...(295, 4) (DV defects with a period of ∆R DV /a = 10 are periodically situated in the zGNR).…”

“…The dashed rectangle represents a pristine unit cell. Following the conventional notation [56,[141][142][143][144][145], the length (L) and the width (N) of the nanoribbon with zigzagshaped edges on both sides are defined as the number of unit cells and zigzag lines across the ribbon's width, respectively. As shown in this figure, each atom is labeled with a pair of numbers (m, n), for which m, n represent the x and y coordinates of the lattice points.…”

“…) Finally, after straightforward calculations, the normalized RKKY interaction can be expressed as the following desired result [141][142][143][144][145]…”

Probing divacancy defects in a zigzag graphene nanoribbon through RKKY exchange interaction

“…The dashed rectangle represents the pristine unit cell. Following the conventional notation [42,[85][86][87][88][89], the length (L) and the width(N ) of the nanoribbon with zigzag shaped edges on both sides are defined as the number of the unit cells and the number of zigzag lines across the ribbon width, respectively. As shown in this figure, each atom is labeled with a pair of numbers (m, n), which m, n represent the x and y coordinates of the lattice points.…”

“…Finally, after straightforward calculations, the normalized RKKY interaction can be expressed in the following desired result [85][86][87][88][89]…”