Transition Metal and Vacancy Defect Complexes in Phosphorene: A Spintronic Perspective

Abstract

Inducing magnetic moment in otherwise nonmagnetic two-dimensional semiconducting materials is the key first step to design spintronic materials. Here, we study the absorption of transition-metals on pristine and defected single-layer phosphorene, within density functional theory. We predict that increased transition-metal diffusivity on pristine phosphorene would hinder any possibility of controlled magnetism, and thus any application. In contrast, the point-defects will anchor metals, and exponentially reduce the diffusivity. Similar to other two-dimensional materials, metals bind strongly on both pristine and defected phosphorene, and we provide a microscopic description of bonding, which explain the qualitative trend with increasing number of valence electrons. We further argue that the divacancy complex is imperative in any practical purpose due to their increased thermodynamic stability over monovacancy. For most cases, the defecttransition metal complexes retain the intrinsic semiconduction properties, and also induce a local magnetic moment with large exchangesplitting and spin-flip energies, which are necessary for spintronic applications. Specifically, the V/Mn/Fe absorbed at the divacancy have tremendous promise in this regard. Further, we provide a simple microscopic model to describe the local moment formation in these transition metal and defect complexes. We also note that metal absorption may completely alter the intrinsic semiconducting nature and give rise to half-metallic and metallic composite system.

Prospects of spintronics based on 2D materials

“…Based on results of first‐principles calculations, adsorption of metal and other atoms do lead to magnetism in some cases, even though the predictions from different calculations can differ significantly, as can be seen in Tables . Similar to graphene, vacancies and other point defects in 2D materials can anchor metals on their surfaces and reduce the diffusivity and formation of metal clusters . Magnetic properties of TM‐doped MoS 2 have been investigated in many first‐principles studies which consistently predicted that Mn‐, Fe‐, and Co‐doped MoS 2 are magnetic .…”

Photocatalytic Activity of Phosphorene Derivatives: Coverage, Electronic, Optical and Excitonic properties

“…The quasiparticle gap is experimentally measured to be in 2.05−2.20 eV range through scanning tunnelling spectroscopy and photo-luminescence excitation spectroscopy. [26,46] While it is known that the conventional exchange-correlational functionals underestimate the gap (PBE: 0.95 eV), [24] the HSE06 hybrid functional (1.4 -1.7 eV) [25,47,48] and many-body perturbation based GW (2.00 -2.25) [49,50] calculations improve the results. As the GW calculations are computationally very expensive for the systems that we have investigated in this paper, we resort to HSE06 functional throughout the present investigation for electronic structure.…”

Engineering the Kondo state in two-dimensional semiconducting phosphorene

“…[21,32,33] The divacancy (DV) with 5-8-5 ring structure is the thermodynamically most stable point defect in SLP. While the conventional PBE functional underestimates the DV-SLP gap to 0.97 eV, the hybrid HSE06 functional (1.77 eV) improves the result.…”

“…It is known that point defects do not alter the intrinsic semiconducting nature of phosphorene. [21,33] In contrast, Cr absorption at the DV induces electronic phase transition, and becomes half-metallic, as shown in Figure 5(a) within PBE exchange correlation functional. The picture remains same while explicit on-site Coulomb interaction is added to the PBE functional or within hybrid HSE06 calculations as shown in Figures 5(b) and (c), respectively.…”

“…[18][19][20] We engineer two-dimensional semiconducting phosphorene such that it becomes susceptible to many-body Kondo screening. While Sc and Cu impurities absorbed on single-layer phosphorene (SLP) triggers semiconductor to metal transition without impurity moment formation, [21,22] the V, Mn, and Fe impurities generate unscreened moments as the systems remain semiconducting. [21] In sharp contrast, while absorbed at the thermodynamically most stable divacancy defect, Cr impurity retains a localized moment, and also alters the electronic structure of phosphorene such that it becomes susceptible to Kondo screening.…”