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The recent demonstration of the growth of two-dimensional (2D) antimony-arsenic alloys provides an additional degree of freedom to tailor the basic properties of the emerging group-V 2D materials. With this perspective, herein, we propose and conduct a comprehensive first-principles investigation on this 2D group-V antimony arsenide (2D As x Sb y), in both free-standing form as well as on the common substrates of Ge(111), Si(111), bilayer graphene, and bilayer hexagonal boron nitride (h-BN). Structural and electronic properties of the 2D As x Sb y are evaluated for different compositions, different types of atomic arrangements for each composition, and different lattice matched interfacial configurations of the composite heterostructures for the four substrates. These systematic studies provide property benchmarks for this new class of group-V 2D materials. This analysis reveals microscopic origins of the interfacial interactions, orbital hybridization, charge transfer, and the resulting electronic structures of the 2D alloy. We predict that a change in the frontier states leads to an indirect-direct bandgap transition according to atomic arrangements in the monolayer As x Sb y. On substrates, the relatively strong interfacial interaction between Ge or Si with As x Sb y suppresses the semiconducting properties exhibited in free layers, while the weak van der Waals interaction between graphene or h-BN with As x Sb y preserves the bands of the alloy. We conclude that 2D group-V alloys As x Sb y give a large material phase-space with very interesting electronic properties. [ABSTRACT FROM AUTHOR]

The temperature dependences of magnetization, electrical transport, and thermal transport properties of antiperovskite compound SnCMn3 have been investigated systematically. A positive magnetoresistance (∼11%) is observed around the ferrimagnetic-paramagnetic transition (TC∼280 K) in the field of 50 kOe, which can be attributed to the field-induced magnetic phase transition. The abnormalities of resistivity, Seebeck coefficient, normal Hall effect, and thermal conductivity near TC are suggested to be associated with an abrupt reconstruction of electronic structure. Further, our results indicate an essential interaction among lattice, spin, and charge degrees of freedom around TC. Such an interaction among various degrees of freedom associated with sudden phase transition is suggested to be characteristic of Mn-based antiperovskite compounds. [ABSTRACT FROM AUTHOR]

Using first-principles calculations within the generalized gradient approximation, we predicted the lattice parameters, elastic constants, vibrational properties, and electronic structure of cementite (Fe3C). Its nine single-crystal elastic constants were obtained by computing total energies or stresses as a function of applied strain. Furthermore, six of them were determined from the initial slopes of the calculated longitudinal and transverse acoustic phonon branches along the [100], [010], and [001] directions. The three methods agree well with each other; the calculated polycrystalline elastic moduli are also in good overall agreement with experiments. Our calculations indicate that Fe3C is mechanically stable. The experimentally observed high elastic anisotropy of Fe3C is also confirmed by our study. Based on electronic density of states and charge density distribution, the chemical bonding in Fe3C was analyzed and was found to exhibit a complex mixture of metallic, covalent, and ionic characters. [ABSTRACT FROM AUTHOR]

The electronic structure and transport properties of donor doped SrTiO3 are studied using density functional theory with spin-orbit coupling and conductivity, Hall, and Seebeck effect measurements over a wide temperature range (100 K to 600 K). Split-off energies ΔSO are tunable through the dopant SO interaction strength and concentration varying from 28.1 meV for pure STO to 70.93 meV for SrTi0.5Nb0.5O3. At lower carrier concentrations and temperatures, SO coupling has a marked effect on both the filling dependence of the density-of-states mass as well as the temperature dependence of the Seebeck coefficient, with quantitative theoretical predictions based on DFT calculations that include the SO interaction in closer agreement to the experimental data. Moreover, the results suggest that the predictive power of the current theory is not unlimited, with less accuracy for the calculated S predicting the magnitude of the experimental S data at lower dopant concentrations than for degenerately doped systems. A concentration dependent mass enhancement of ∼2-5, relative to the density-of-states mass in the local density approximation, possibly due to the influence of electronic screening of the electron-phonon interaction, would bring the theoretical S in accord with the experimental S data. This additional carrier-dependent enhancement mechanism for S may give an additional degree of freedom in terms of designing new higher efficiency thermoelectric energy materials. [ABSTRACT FROM AUTHOR]