Dirac Cones, Elastic Properties, and Carrier Mobility of the FeB₂ Monolayer: The Effects of Symmetry

Abstract

Among the rare two-dimensional Dirac materials with novel properties, the FeB 2 monolayer with a planar honeycomb structure was expected to be a promising candidate for spintronic devices due to its symmetry. Here, we combined group-theory analysis and first-principles calculations to investigate the band structure and the intrinsic carrier mobility of the FeB 2 monolayer under acoustic phonon scattering conditions. The Dirac cones were found to be isotropic with a Fermi velocity of 3.98 × 10 5 m/ s, being about a half of that in graphene. The Dirac point is a singular point whose projected orbital components are dependent on the approaching direction. Based on the generalized deformation potential theory, the carrier mobility of the FeB 2 monolayer at room temperature was predicted to be about 5.8 × 10 4 cm 2 V −1 s −1 and was less vulnerable to charge doping in comparison with graphene.

Novel Piezoelectricity in Two-Dimensional Metallic/Semimetallic Materials with Out-of-Plane Polarization

“…B atoms form a graphene-like honeycomb grid with a lattice constant of 3.178 Å, while Fe atoms are located at a vertical distance of h = 0.63 Å above the hexagonal center. These results are entirely consistent with earlier studies. , The separated layered structure of B and Fe makes the system resemble a parallel-plate capacitor with opposite charges on two layers. The potential energy profile for electrons along the out-of-plane direction is plotted in Figure b.…”

“…In this study, we focus on out-of-plane polarization and its corresponding piezoelectricity. For the system we studied (FeB 2 monolayer), due to its p 6 mm symmetry, the system is isotropic with the x and y directions being equivalent, , so we have C 11 = C 22 , e 31 = e 32 , d 31 = d 32 , and d 31 = e 31 C 11 + C 12 The source of piezoelectric effect is often divided into an electronic term and ionic term . To obtain the electronic contribution, all ions should be clamped to their own fractional coordinates when applying strains.…”

“…For example, it possesses an elastic modulus of 141 N/m for Young’s modulus and a thermal conductivity of 52 W/mK . It is a nonmagnetic system and has a high intrinsic carrier mobility of 0.58 × 10 5 cm 2 V –1 s –1 which is less affected by charge doping . Recently, quantum anomalous Hall effect associated with Chern number has been predicted in FeB 2 monolayer …”

Quasi-Two-Dimensional Nanostructures from AlB2-Type Metal Borides: Physicochemical Insights and Emerging Trends

“…Therefore, several new opportunities for researchers are available to successfully realize the great potential that this class of materials has to offer. Theoretical reports have already predicted these borides to be useful for unique applications such as ferromagnetism, coating films, spintronic devices, optical materials, functional ceramics, , and also novel catalysts. , The ensuing section of this review will detail some of the applications that have been realized.…”

First-Principles Study of FeB2Monolayers as High-Capacity Electrode Materials for Mg-Ion Batteries

“…Graphene as the typical 2D Dirac material has received extensive attention and research in the field of rechargeable batteries. , Recently, Zhang et al discovered a new 2D Dirac material with a graphene-like FeB 2 monolayer by density functional theory (DFT) calculations . It is the global minimum 2D FeB 2 system that has a Fermi velocity in the same order as graphene and has been studied in mechanical and electronic properties, effects of symmetry, and so on. Despite these advances, FeB 2 has not been investigated as an electrode material for rechargeable batteries now.…”