Modification of electronic structure, magnetic structure, and topological phase of bismuthene by point defects

Abstract

This paper reveals how the electronic structure, magnetic structure, and topological phase of two-dimensional (2D), single-layer structures of bismuth are modified by point defects. We first showed that a free-standing, single-layer, hexagonal structure of bismuth, named h-bismuthene, exhibits nontrivial band topology. We then investigated interactions between single foreign adatoms and bismuthene structures, which comprise stability, bonding, electronic structure, and magnetic structures. Localized states in diverse locations of the band gap and resonant states in band continua of bismuthene are induced upon the adsorption of different adatoms, which modify electronic and magnetic properties. Specific adatoms result in reconstruction around the adsorption site. Single vacancies and divacancies can form readily in bismuthene structures and remain stable at high temperatures. Through rebondings, Stone-Whales-type defects are constructed by divacancies, which transform into a large hole at high temperature. Like adsorbed adatoms, vacancies induce also localized gap states, which can be eliminated through rebondings in divacancies. We also showed that not only the optical and magnetic properties, but also the topological features of pristine h-bismuthene can be modified by point defects. The modification of the topological features depends on the energies of localized states and also on the strength of coupling between point defects.

Two-dimensional pnictogens: A review of recent progresses and future research directions

“…Nitrogene, 44 phosphorene, 34 arsenene, 45 antimonene, 46 and bismuthene 48 have recently gained importance due to their semiconducting properties. Furthermore, due to the large spin-orbit coupling effects shown by antimonene, bismuthene, and their compounds, 48,[131][132][133] these layered structures have attracted special interest owing to their possible topologically non-trivial states in specific conditions. Apparently, as the row number increases, the topological insulator properties stand out gradually.…”

“…[184][185][186][187][188][189][190][191] Also, hb-Bi placed on the Si(0001) substrate was shown to possess a topologically non-trivial phase. 192 Kadioglu et al 132 found that while the pristine hb-Bi monolayer displays topologically non-trivial behavior, aw-Bi does not. Not only pristine and bare Bi ultrathin films and monolayers, but also the topological behaviors of defected Bi structures have been subject of studies.…”

“…Interaction of the adatoms, H, C, O, Si, P, Ge, As, Se, Sb, Pb, Sn, and Te with hb-Bi and aw-Bi bismuthene phases has been investigated using DFT calculations. 132 They found that the binding energies are high (ranging from 1.1 eV to 4.1 eV) and are dominated by chemical bonding through charge exchange between the adatoms and nearest host Bi atoms. The vdW contribution to the binding energies is generally small except for the bonding of Si and Sb to hb-Bi.…”

Structure dependent optoelectronic properties of monolayer antimonene, bismuthene and their binary compound

“…36 Monolayer hb-bismuthene is topologically non-trivial based on the density functional theory (DFT)-spin-orbit coupling (SOC) calculations. 37 Also, hb-Bi placed on a Si substrate was shown to be topologically non-trivial. DFT-SOC calculations of aw-Bi indicated a trivial topological order.…”

“…DFT-SOC calculations of aw-Bi indicated a trivial topological order. 37 (v) Finally, significant progress has been made towards the synthesis of SL antimonene and bismuthene structures. Ultrathin films of antimonene have been synthesized using methods such as mechanical/liquid-phase exfoliation or epitaxial growth.…”