Electronic structure and magnetism in doped semiconducting half-Heusler compounds

We have studied in details the electronic structure and magnetism in M (Mn and Cr) doped semiconducting half-Heusler compounds FeVSb, CoTiSb and NiTiSn (XM$_{x}$Y$_{1-x}$Z) in a wide concentration range using local-spin density functional method in the framework of tight-binding linearized muffin tin orbital method(TB-LMTO) and supercell approach. Our calculations indicate that some of these compounds are not only ferromagnetic but also half-metallic and may be useful for spintronics applications. The electronic structure of the doped systems is analyzed with the aid of a simple model where we have considered the interaction between the dopant transition metal (M) and the valence band X-Z hybrid. We have shown that the strong X-d - M-d interaction places the M-d states close to the Fermi level with the M-t$_{2g}$ states lying higher in energy in comparison to the M-e$_{g}$ states. Depending on the number of available d-electrons, ferromagnetism is realized provided the d-manifold is partially occupied. The tendencies toward ferromagnetic(FM) or antiferromagnetic(AFM) behavior are discussed within Anderson-Hasegawa models of super-exchange and double-exchange. In our calculations for Mn doped NiTiSn, the strong preference for FM over AFM ordering suggests a possible high Curie temperature for these systems.Comment: 14 pages, 6 figure

Two Dimensional Spin-Polarized Electron Gas at the Oxide Interfaces

The formation of a novel spin-polarized 2D electron gas at the LaMnO$_3$ monolayer embedded in SrMnO$_3$ is predicted from the first-principles density-functional calculations. The La (d) electrons become confined in the direction normal to the interface in the potential well of the La layer, serving as a positively-charged layer of electron donors. These electrons mediate a ferromagnetic alignment of the Mn t$_{2g}$ spins near the interface via the Anderson-Hasegawa double exchange and become, in turn, spin-polarized due to the internal magnetic fields of the Mn moments.Comment: 5 pages, 6 figure

Banking Deregulations, Financing Constraints and Firm Entry Size

We examine the effect of US branch banking deregulations on the entry size of new firms using micro-data from the US Census Bureau. We find that the average entry size for startups did not change following the deregulations. However, among firms that survived at least four years, a greater proportion of firms entered either at their maximum size or closer to the maximum size in the first year. The magnitude of these effects were small compared to the much larger changes in entry rates of small firms following the reforms. Our results highlight that this large-scale entry at the extensive margin can obscure the more subtle intensive margin effects of changes in financing constraints.entrepreneurship, entry size, financial constraints, banking.

Financing Constraints and Entrepreneurship

Abstract is not available at this time

Strain and Electric Field Modulation of the Electronic Structure of Bilayer Graphene

We study how the electronic structure of the bilayer graphene (BLG) is changed by electric field and strain from {\it ab initio} density-functional calculations using the LMTO and the LAPW methods. Both hexagonal and Bernal stacked structures are considered. The BLG is a zero-gap semiconductor like the isolated layer of graphene. We find that while strain alone does not produce a gap in the BLG, an electric field does so in the Bernal structure but not in the hexagonal structure. The topology of the bands leads to Dirac circles with linear dispersion in the case of the hexagonally stacked BLG due to the interpenetration of the Dirac cones, while for the Bernal stacking, the dispersion is quadratic. The size of the Dirac circle increases with the applied electric field, leading to an interesting way of controlling the Fermi surface. The external electric field is screened due to polarization charges between the layers, leading to a reduced size of the band gap and the Dirac circle. The screening is substantial in both cases and diverges for the Bernal structure for small fields as has been noted by earlier authors. As a biproduct of this work, we present the tight-binding parameters for the free-standing single layer graphene as obtained by fitting to the density-functional bands, both with and without the slope constraint for the Dirac cone.Comment: 7 pages, 7 figure

Designing Verbal Message And Visual Media Of Quick Chicken

Quick Chicken currently exists on more than 8 islands, more than 17 provinces, more than 220 outlets. Compared to similar fried chicken outlets, Quick Chicken outlet designs are more attractive because they use the concept of selling in containers. The advantages of Quick Chicken are offering a menu that is a combination of traditional and western, in addition, Quick Chicken also offers larger pieces of chicken than its competitors, namely Hisana and Sabana. Currently Quick Chicken is experiencing a decline in sales. This happens because the promotion done has not been able to make the target audience aware and loyal. The question research is how to design verbal message and visual media as the solustion for the problem above. Semantics is used to define the verbal message, while advertising theory is used as the the grand theory of visual media. The methode used is qualitative descriptif. The result is as the recommendation design of the verbal message and visual media as the solution for the problem using AISAS. The conclusion is with the design of Quick Chicken promotion, it is hoped that being able to be a solution to identified problems, and it can also be a reference for similar problems as well. Key Words: Semantics, verbal message, Visual Media, Quick Chicke