KTlO: a metal shrouded 2D semiconductor with high carrier mobility and tunable magnetism

Abstract

Two-dimensional (2D) materials with high carrier mobility and tunable magnetism are in high demand for nanoelectronics and spintronic applications. Herein, we predict a novel two-dimensional monolayer KTlO that possesses an indirect band gap of 2.25 eV (based on HSE06) and high carrier mobility (1.86×10 3 cm 2 V -1 s -1 for electron and 2.54 ×10 3 cm 2 V -1 s -1 for hole) by means of ab initio calculations. KTlO monolayer has a calculated cleavage energy of 0.56 J m -2 , which suggests exfoliation of bulk material as viable means for the preparation of mono-and few-layer materials. Remarkably, the KTlO monolayer suggests tunable magnetism and half-metallicity with hole doping, which are attributed to the novel Mexican-hat-like bands and van Hove singularities in its electron structure. Furthermore, monolayer KTlO exhibits moderate optical 2 absorption over visible light and ultraviolet region. The band gap value and band characteristics of monolayer KTlO can be strongly manipulated by biaxial and uniaxial strains to meet the requirements of various applications. All these novel properties render monolayer KTlO a promising functional material for future nanoelectronics and spintronic applications.

Single-Layer Dititanium Oxide Ti2O MOene: Multifunctional Promises for Electride, Anode Materials, and Superconductor

“…Following remarkable promises of conventional MSM, metal-shrouded monochalcogenides, such as single-layer (SL) Tl 2 O, A 2 X (A = Na, K, Rb, or Cs; X = O, S, Se, or Te), KTlO, and In 2 X (X = O, S, Se), have also showed fascinating physical and chemical traits, substantially enriching the family of 2D MSC. Considering the potential uses, the toxicity and scarcity of element Tl (as rare as gold) and the highly activity of alkali metals when exposed to ambient conditions seem to be detrimental.…”

Carrier doping-induced strong magnetoelastic coupling in 2D lattice

“…[57][58][59] It is worth noting that obvious structural phase transition from 2D to the one-dimensional-like framework of 2D β-PbO is observed in the doping process when the doping density surpass 9.40 × 10 14 cm −2 (2.6 hole per unit cell), which is also the critical point for the sudden surge of magnetic energy and is similar to previous report. 60 To show this more clearly, the evolution of lattice constants and final structure are shown in Fig. S4(a).…”

BaAs3: a narrow gap 2D semiconductor with vacancy-induced semiconductor–metal transition from first principles

“…2c. The DFT-estimated exfoliation energy of ML BaAs3 is larger than that of graphite (0.37 J m -2 from experimental and 0.32 J m -2 in theory) [41,42] but at the same level of InP3 (1.32 J m -2 ) [14], GeP3 (1.14 J m -2 ) [15], CaP3 (1.30 J m -2 ) [18] and CaAs3(1.36 J m -2 ) [19]. Therefore, in principle ML BaAs3 crystal could be prepared experimentally from its bulk counterpart using mechanical cleavage or liquid phase exfoliation.…”

“…For 2D semiconductors, Lang et al [49] recently gave a new formula for the acoustic phonon-limited mobility, taking into account the anisotropic elastic constants or deformation potential constants. For nonisotropic 2D materials, the theoretical carrier mobility can be calculated by the following equation [42,49,50] Indeed, the  angle is 73.19° that could not simply be approximated as 90°. Therefore, for ML BaAs3 we adopt an orthogonal supercell (shown in Fig.2a) to calculate the carrier mobility.…”