Theory of skyrmion, meron, anti-skyrmion and anti-meron in chiral magnets

We find closed-form solution of the Euler equation for a chiral magnet in terms of a skyrmion or a meron depending on the relative strengths of magnetic anisotropy and magnetic field. We show that the relevant length scales for these solutions primarily depend on the strengths of Dzyaloshinskii-Moriya interaction through its ratios, respectively, with magnetic field and magnetic anisotropy. We thus unambiguously determine the parameter dependencies on the radius of the topological structures particularly of the skyrmions, showing an excellent agreement with experiments and first-principle studies. An anisotropic Dzyaloshinskii-Moriya interaction suitable for thin films made with $C_{nv}$ symmetric materials is found to stabilize anti-skyrmion and anti-meron, which are prototypical for $D_{2d}$ symmetric systems, depending on the degree of anisotropy. Based on these solutions, we obtain phase diagram by comparing the energies of various collinear and non-collinear competing phases.Comment: 8 pages, 8 figure

Direct Evidence of Mg Incorporation Pathway in Vapor-Liquid-Solid Grown p-type Nonpolar GaN Nanowires

Doping of III-nitride based compound semiconductor nanowires is still a challenging issue to have a control over the dopant distribution in precise locations of the nanowire optoelectronic devices. Knowledge of the dopant incorporation and its pathways in nanowires for such devices is limited by the growth methods. We report the direct evidence of incorporation pathway for Mg dopants in p-type nonpolar GaN nanowires grown via vapour-liquid-solid (VLS) method in a chemical vapour deposition technique for the first time. Mg incorporation is confirmed using X-ray photoelectron (XPS) and electron energy loss spectroscopic (EELS) measurements. Energy filtered transmission electron microscopic (EFTEM) studies are used for finding the Mg incorporation pathway in the GaN nanowire. Photoluminescence studies on Mg doped GaN nanowires along with the electrical characterization on heterojunction formed between nanowires and n-Si confirm the activation of Mg atoms as p-type dopants in nonpolar GaN nanowires.Comment: 29 pages, 6 figures, journa

Secondary xylary features in proving truth/falsity of an alibi: examples of three important Indian commercial woods

Secondary xylary characters of wood are useful to identify a wood up to its generic or specific level and thus may prove or disprove the alibi of the retailers i.e., a wood is genuine or not. In the present study, 26 wood samples were collected from the local markets of Baruipur, Sealdah and Garia in Kolkata, West Bengal. Among them, 8 were sold as ‘Sandal wood’ (Santalum album), 4 as ‘Red Sanders’ (Pterocarpus santalinus) and 14 as ‘Sal wood’ (Shorea robusta). Results indicate that xylotomical features of most of the collected ‘sandal wood’ and ‘red sander’ samples did not match with the reference Santalum album and Pterocarpus santalinus samples whereas most of the collected ‘Sal wood’ samples from furniture shops matched with the reference samples of Shorea robusta. Present study successfully indicates that xylotomical investigations of commercial wood may establish the authenticity of wood of commerce

O termoelektričnoj snazi u inverznim slojevima n–tipa na tetragonalnim materijalima u paralelnom magnetskom polju

We present a simplified analysis of thermoelectric power of carriers in n-channel inversion layers on tetragonal materials under the limits of weak and strong electric field, in the presence of a parallel magnetic field, at low temperatures. Taking n-channel inversion layers of CdGeAs2 as an example, on the basis of a newly formulated 2D generalized electron energy spectra within the framework of k^→ p^→ formalism incorporating various anisotropies of the energy band constants, it is found that thermoelectric power increases with decreasing surface electric field for both limits in oscillatory manners which are totally band structure dependent. The crystal field splitting reduces its numerical values. The thermopower exhibits oscillatory increment with increasing alloy composition for 2D system of ternary materials. The corresponding well-known results for the two-band Kane model in the absence of magnetic field have been obtained under certain limiting conditions as special cases of our generalized analysis.Izlažemo pojednostavljenu analizu termoelektrične snage pokretnih nositelja naboja u inverznim slojevima n–tipa na tetragonalnim materijalima u granicama slabog i jakog električnog polja, u magnetskom polju i na niskim temperaturama. Na primjeru inverznih slojeva CdGeAs2 n–tipa, na osnovi novih 2D generaliziranih elektronskih energijskih spektara i u okviru k^→ p^→ formalizma uz različite anizotropije konstanata energijskih vrpci, utvrđeno je da termoelektrična snaga raste sa smanjenjem površinskog električnog polja na obje granice, uz oscilacije koje su potpuno ovisne o strukturi vrpce. Cijepanje kristalnog polja smanjuje termoelektričnu snagu. Termoelektrična snaga pokazuje oscilacijsko povećanje pri povećanom sastavu za 2D sisteme ternarnih materijala. Poznati rezultati dvo–vrpčastog Kaneovog modela se dobivaju uz neke granične uvjete kao posebni slučajevi naše općenite analize

Molecular diversity and association of simple sequence repeat markers with kernel mass in cultivated groundnut (Arachis hypogaea L.)

Abstract Groundnut yield can be further enhanced by improving pod and kernel size vis-a-vis mass. Marker assisted breeding will be an ideal option for directed improvement of hundred kernel mass. A study was undertaken to detect molecular diversity using 35 SSRs in 12 mutant genotypes, developed through chemical mutagenesis, from an interspecific large kernel size pre-breeding line and to identify markers associated with kernel mass. SSRs yielded an average of 3.57 polymorphic bands per primer. Average polymorphism and PIC were 64.95% and 0.62, respectively. Cluster analysis revealed two main clusters separated at 61% Jaccard's similarity coefficient. Vast of the genotypes were grouped into single cluster, confirming common pedigree of these genotypes. AMOVA among 12 mutant genotypes and their parent detected 15% of total variation associated with kernel mass. K-W ANOVA detected significant association of five SSRs with kernel mass. Among these associated primers, TC3A12 and TC9H09 accounted for 28% and 12% of phenotypic variation due to kernel mass and were associated with major QTLs. Out of these two associated primer, TC3A12 differentiated genotypes with higher kernel mass from genotypes with lower kernel mass by amplifying a band of approximately of 450bp. Thus association of TC3A12 primer with a major QTL of kernel mass was further validated in genotypes with diverse background. The TC3A12 primer discriminated genotypes with higher kernel mass from genotype with lower kernel mass by amplifying the band of 400bp among genotypes with higher kernel mass