Abstract
Using first-principles calculations based on the density functional theory, the effects of atomic vacancy defect, Frenkel-type defect and transition metal Z (Z = Sc, V and Zr) doping on magnetic and electric properties of the Ti4N3 MXene nanosheet were investigated comprehensively. The surface Ti and subsurface N atomic vacancies are both energetically stable based on the calculated binding energy and formation energy. In addition, the former appears easier than the latter. They can both enhance the magnetism of the Ti4N3 nanosheet. For atom-swapped disordering, the surface Ti-N swapped disordering is unstable, and then the Frenkel-type defect will happen. In the Frenkel-type defect system, the total magnetic moment decreases due to the enhancement of indirect magnetic exchange between surface Ti atoms bridged by the N atom. A relatively high spin polarizability of approximately 70% was detected. Furthermore, the doping effects of transition metal Z (Z = Sc, V and Zr) on Ti4N3 nanosheet are explored. All doped systems are structurally stable and have relatively large magnetism, which is mainly induced by the directed magnetic exchange between surface Z and Ti atoms. Especially in the doped Ti4N3-Sc system, the high spin polarizability is still reserved, suggesting that this doped system can be a potential candidate for application in spintronics.
Highlights
Graphene was discovered in 2004, breaking the classical theory that thermodynamic fluctuations do not happen in any two-dimensional (2D) crystal at a finite temperature [1,2]
We focused on the atomic vacancy defect of the Ti4 N3 nanosheet
The atomic vacancy defect, Frenkel-type defect and transition metal Z (Z = Sc, V, Zr) doping in Ti4 N3 MXene nanosheet were investigated comprehensively by the first-principles calculation based on density functional theory
Summary
Graphene was discovered in 2004, breaking the classical theory that thermodynamic fluctuations do not happen in any two-dimensional (2D) crystal at a finite temperature [1,2]. Graphene had shown many excellent physical and chemical properties into wide material applications, such as big specific surface area is (2630 m2 /g) [3], high electron mobility (1.5 × 105 cm2 /v·s) [4], good thermal conductivity (5000 W/m·K) [5], high Young’s modulus (1.0 TPa) [6] and visible light transmittance The zero-band gap of graphene limits its application in the field of electronic devices, leading to a series of studies on graphene-like 2D materials [8], such as hexagonal boron nitride, transition metal sulfur compounds, transition metal oxides, black phosphorus and various. Many graphene-like materials making up for the inadequacy of graphene materials showed better physical and chemical properties, and were applied in optoelectronics, spintronics, catalysis, biological and chemical sensors, lithium/sodium ion batteries, supercapacitors, fuel cells, polymer composite materials and other fields [9].
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