Magnetoelectric Properties of Pb Free Bi2FeTiO6: A Theoretical Investigation

The structural, electronic, magnetic and ferroelectric properties of Pb free double perovskite multiferroic Bi2FeTiO6 are investigated using density functional theory within the general gradient approximation (GGA) method. Our structural optimization using total energy calculations for different potential structures show a minimum energy for a non-centrosymmetric rhombohedral structure with R3 space group. Bi2FeTiO6 is found to be an antiferromagnetic insulator with C-type magnetic ordering with bandgap value of 0.3 eV. The calculated magnetic moment of 3.52 \mu_B at Fe site shows the high spin arrangement of 3d electrons which is also confirmed by our orbital projected density of states analysis. We have analyzed the characteristics of bonding present between the constituents of Bi2FeTiO6 with the help of calculated partial density of states and Born effective charges. The ground state of the nearest centrosymmetric structure is found to be a G-type antiferromagnet with half metallicity showing that by the application of external electric field we can not only get a polarized state but also change the magnetic ordering and electronic structure in the present compound indicating strong magnetoelectric coupling. The cation sites the coexistence of Bi 6s lone pair (bring disproportionate charge distribution) and Ti4+ d0 ions which brings covalency produces off-center displacement and favors a non-centrosymmetric ground state and thus ferroelectricity. Our Berry phase calculation gives a polarization of 48 \muCcm-2 for Bi2FeTiO6.Comment: 4 pages, 5 picture

Prediction of Magnetoelectric behavior in Bi2MnTiO6

We present results from ab initio calculations based on density functional theory for bismuth-based double perovskite Bi2MnTiO6. Using total energy calculation with stress and force minimization we have predicted the equilibrium crystal structure for Bi2MnTiO6 considering potential structures into the calculation. We have predicted that the ground state of Bi2MnTiO6 will be a noncentrosymmetric rhombohedral structure with space group R3c. Our spin polarized calculation for different possible collinear magnetic configurations we found that Bi2MnTiO6 will be an insulator with G-type antiferromagnetic ordering in its ground state. The coexistence of both stereochemically active Bi-6s lone pair and the Ti4+ with d0-ness which bring covalency results in the stabilization of noncentrosymmetric structure and thus ferroelectricity. Our orbital projected density of states plot shows that the Mn2+ in Bi2MnTiO6 will be at high spin state with a spin moment of 4.28 {\mu}B. Hence Bi2MnTiO6 is predicted to be a magnetoelectric material.Comment: 3 pages, submitted to proceedings for the "61st DAE Solid State Physics Symposium" Bhubaneswar, Odisha, Indi

Mechanical properties of 2D materials: A review on molecular dynamics based nanoindentation simulations

The study of the mechanical properties of two-dimensional (2D) materials is one of the most pursued areas of materials research. Nanoindentation, an experimental technique, is commonly used to determine the mechanical strength of materials, ranging from 2D materials to bulk. It can also be simulated using the molecular dynamics method, thereby providing atomic-level insights into the material\u27s mechanical response. In this paper, we review the results obtained for 2D materials, including atomically thin monolayers to a few nanometer-thick thin films in the scientific literature. We find that an accurate description of chemical bonding is essential in these materials to gain an insight into their in-plane (or out-of-plane) mechanical response, which can be exploited in next-generation nanoscale devices

Orientation-Dependent Electronic and Mechanical Properties of Tungsten Nitride Nanosheets: Implications for Flexible Devices

Transition metal nitrides play an essential role in various technological applications due to their superior mechanical properties and high chemical stability. The synthesis and characterization of WN nanosheets further affirmed the role of transition metal nitrides as coatings that enable materials to be mechanically robust. In this paper, we report the results of a theoretical study based on density functional theory and molecular dynamics simulations focusing on the surface orientation and termination-dependent structural, electronic, and mechanical properties of WN nanosheets. The results suggest that the W-terminated (0001) nanosheet is energetically preferable and easily grown on a substrate. Moreover, the metallic nature is robust in the designed nanosheets regardless of the growth direction or surface termination. A relatively high mechanical strength is predicted for W-terminated and non-polar nanosheets, whereas N-terminated nanosheets exhibit fracture strain values comparable to graphene and BN monolayers. The results demonstrate that the mechanical strength of these nanosheets can be tuned by the growth directions and terminations, which suggests that they can be promising candidates for designing mechanically strong and flexible devices

Stability and electronic properties of the graphene-supported FeO nanostructures including clusters and monolayer

Integration of graphene with subnano clusters or monolayer of FeO can facilitate the formation of nanostructures with applications in magnetic storage or health-related areas. In this paper, first-principles calculations are performed to investigate the stability and electronic properties of such supported nanostructures. The results show that a noticeable hybridization occurs between Fe and C atoms at the interface that provide stability to both the clusters and monolayer on graphene. The substrate-induced changes in the electronic properties of the (FeO)n clusters are small since the clusters appeared to be weakly adsorbed on the surface. However, this is not the case with FeO(111) monolayer for which a buckled configuration is predicted to be energetically preferred on graphene. Subsequently, graphene-supported FeO(111) monolayer exhibits half-metallicity with ferrimagnetic alignment of the magnetic moments in the lattice with finite total magnetic moment. The interface bonding, therefore, appears to define the characteristics of graphene-supported FeO(111) monolayer, though it makes small but noticeable changes in the graphene-supported (FeO)n clusters