Strain-induced modulation of exchange interaction in monolayer zigzag nanoribbons of B$_2$S
In this work, the strain modulation of electronic structure and magnetic interaction in monolayer nanoribbons of B$_2$S, 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 B$_2$S 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 B$_2$S. We show that breaking inversion symmetry in zigzag B$_2$S 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 $\varepsilon_x$ and $\varepsilon_y$. 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. The magnetic interactions between adsorbed magnetic impurities in B$_2$S 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 B$_2$S nanoribbons.