Ferromagnetism in two-dimensional hole-doped SnO

M Houssa,K Iordanidou,A Stesmans,V V Afanas’Ev,G Pourtois

doi:10.1063/1.5025272

Abstract

Hole-doped monolayer SnO has been recently predicted to be a ferromagnetic material, for a hole density typically above 5x1013/cm2. The possibility to induce a hole-doped stable ferromagnetic order in this two-dimensional material, either by intrinsic or extrinsic defects, is theoretically studied, using first-principles simulations. Sn vacancies and Sn vacancy-hydrogen complexes are predicted to be shallow acceptors, with relatively low formation energies in SnO monolayers grown under O-rich conditions. These defects produce spin-polarized gap states near the valence band-edge, potentially stabilizing the ferromagnetic order in 2D SnO. Hole-doping resulting from substitutional doping is also investigated. Among the considered possible dopants, As, substituting O, is predicted to produce shallow spin-polarized gap states near the valence band edge, also potentially resulting in a stable ferromagnetic order in SnO monolayers.

Highlights

Hole doping of 2D SnO has been theoretically predicted to induce a paramagnetic to ferromagnetic phase transition in this 2D material, for a hole density above typically 5x1013 cm-2.15 Ferromagnetism in monolayer SnO arises from an exchange splitting of electronic states at the top of the valence band, where the density of states exhibits a sharp Van Hove singularity, resulting in a so-called Stoner instability.[15]
Hole-doped monolayer SnO, with a typical hole density above 5x1013 cm-2, is predicted to be a ferromagnetic material, which could be of much interest in future 2D spintronic devices
Sn vacancies and hydrogen-Sn vacancy complexes have been found to behave like acceptors, with a relatively low formation energy, especially under O-rich growth conditions

Summary

Introduction

Two-dimensional (2D) materials, like graphene, transition metal (di)chalcogenides and Xenes (X:Si, Ge or Sn) are currently attracting considerable interest due to their promising applications in novel nanoelectronics devices.[1,2,3,4,5] Among 2D metal oxides, ZnO and SnO are gaining attention.[6,7,8] SnO is a layered (van der Waals) material, which has already been integrated as the active channel in functional ambipolar thin-film transistors[9,10,11,12] and metal-oxide-semiconductor field-effect transistors.[13] Recently, van der Waals p-n heterojunctions based on SnO and few layer MoS2 have been fabricated.[14] Very interestingly, hole doping of 2D (monolayer) SnO has been theoretically predicted to induce a paramagnetic to ferromagnetic phase transition in this 2D material, for a hole density above typically 5x1013 cm-2.15 Ferromagnetism in monolayer SnO arises from an exchange splitting of electronic states at the top of the valence band, where the density of states exhibits a sharp Van Hove singularity, resulting in a so-called Stoner instability.[15] Hole-doped monolayer SnO shows promise for its possible use in novel 2D spintronic devices.[16]

Methods

Results

Conclusion