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The electronic structure of Sc1-xVxNy epitaxial films with different alloying concentrations of V are investigated with respect to effects on thermoelectric properties. Band structure calculations on Sc0.75V0.25N indicate that V 3d states lie in the band gap of the parent ScN compound in the vicinity of the Fermi level. Thus, theoretically the presence of light (dispersive) bands at the {\Gamma}-point with band multiplicity is expected to lead to lower electrical resistivity while flat (heavy) bands at X-W-K symmetry points are associated with higher Seebeck coefficient than that of ScN. With this aim, epitaxial Sc1-xVxNy thin film samples were deposited on MgO(001) substrates. All the samples showed N substoichiometry and pseudocubic crystal structure. The N-vacancy-induced states were visible in the Sc 2p XAS spectra. The reference ScN and Sc1-xVxNy samples up to x = 0.12 were n type, exhibiting carrier concentration of 1021 cm-3, typical for degenerate semiconductors. For the highest V alloying of x = 0.15, holes became the majority charge carrier as indicated by the positive Seebeck coefficient. The underlying electronic structure and bonding mechanism in Sc1-xVxNy influence the electrical resistivity, Seebeck coefficient, and Hall effect. Thus, the work contributes to the fundamental understanding of the correlated defects and thermoelectric properties to the electronic structure in Sc-N system with V alloying., Comment: 29 pages, 8 figures, 4 tables

CrN-based alloy thin films are of interest as thermoelectric materials for energy harvesting. Ab initio calculations show that dilute alloying of CrN with 3 at.% W substituting Cr, induce flat electronic bands and push the Fermi level EF into the conduction band, while retaining dispersive Cr 3d bands. These features are conducive for both high electrical conductivity \sigma and high Seebeck coefficient \alpha, and hence the thermoelectric power factor {\alpha}^2\sigma. To investigate this possibility, epitaxial CrWxNz films were grown on c-plane sapphire by dc-magnetron sputtering. However, even films with the lowest W concentration (x = 0.03) in our study contained metallic h-Cr2N, which is not conducive for a high \alpha. Nevertheless, the films exhibit a sizeable power factor of {\alpha}^2\sigma ~ 4.7 x 10-4 Wm-1K-2 due to high \sigma ~ 700 Scm-1, and a moderate \alpha ~ -25 ~{^^^^00b5}V/K. Increasing h-Cr2N fractions in the 0.03 < x \le 0.19 range monotonically increases \sigma, but severely diminishes \alpha leading to two orders of magnitude decrease in {\alpha}^2\sigma. This trend continues with x > 0.19 due to W precipitation. These findings indicate that dilute W additions below its solubility limit in CrN is important for realizing high thermoelectric power factor in CrWxNz alloy films.

Large unit cell copper-chalcogenide based minerals with high crystalline anharmonicity have a potential for thermoelectric applications owing to their inherent poor lattice thermal conductivity. Here, the softening of copper-selenium bonding and hence crystal framework plays an important role in superionic conduction and thermal conductivity. We have studied Cu26Nb2Sn6Se32, Cu26Nb2Sn6Se31.5 and Cu26Nb2Sn6Se30Te2 minerals with a strategically tailored anionic disorders. These compounds have p-type degenerate behavior with carrier concentration ranging between 1020 cm-3 at 300 K, high power factor and low lattice thermal conductivity at 640 K. The existence of two low frequency Raman active optical modes associated with soft Cu and Se atoms, three localized Einstein modes in specific heat, suggest high scattering between acoustic and optical branches with very short phonon lifetime less than 1 ps. The excess vibrational density of states at low energies with compressed and flat optical branches strongly hinders the heat transport in these crystalline mineral. Comparatively, Cu26Nb2Sn6Se30Te2 is a promising thermoelectric material because of high crystalline anharmonicity and softening of Cu-Se framework due to heavier tellurium atom., Comment: 20 Pages, 14 figures in main text and supporting information

Anisotropy of light-matter interactions in materials give remarkable information about the phonons and their interactions with electrons. We report the angle-resolved polarized Raman spectroscopy of single-crystal of Bi2Se3 to obtain the elements of Raman tensor for understanding the strength of polarization along different crystallographic orientations. Intensity variation in the polar plots corresponding to E_g^1 ~ 37 cm-1, A_1g^1 ~71 cm-1, E_g^2 ~ 130 cm-1, and A_1g^2 ~ 173 cm-1 suggests the higher differential polarizability along cross-plane (bc-plane). The polar patterns and the differences in elements of the Raman tensor provides the evidence of the fundamental electron-phonon and anisotropic light matter interactions in Bi2Se3., Comment: 11 pages and 4 figures

Ternary chalcogenides, having large crystalline unit cell and van der Waal stacking of layers, are expected to be poor thermal conductors and good thermoelectric (TE) materials. We are reporting that layered Bi4GeTe7, with alternating quintuplet-septuplet layers of Bi2Te3 and Bi2GeTe4, has an ultralow thermal conductivity, \k{appa}total 0.42 Wm-1K-1 because of high degree of anharmonicity as estimated from large Gruneisen parameter ({\gamma} 4.07) and low Debye temperature ({\theta}d 135 K). The electron dominated charge transport has been realized from the Seebeck coefficient, S - 82 uV/K, at 380 K, and Hall carrier concentration of ne ~ 9.8 x 1019 cm-3 at 300 K. Observation of weak antilocalization (WAL), due to spin-orbit coupling (SOC) of heavy Bi and Te, advocate Bi4GeTe7 to be a topological quantum material also. The cross-sectional transmission electron microscopy images show the inherent stacking of hetero-layers, which are leading to a large anharmonicity for poor phonon propagation. Thus, being a poor thermal conductor with a TE figure of merit, ZT ~ 0.24, at 380 K, the Bi4GeTe7 is a good material for TE applications.

We report on structure, vibrational properties and weak-antilocalization-(WAL-) induced quantum correction to magnetoconductivity in single crystal Bi2GeTe4. Surface band structure calculations show a single Dirac cone corresponding to topological surface states in Bi2GeTe4. An estimated phase coherence length, l_{\phi} ~ 143 nm and prefactor {\alpha} ~ - 1.54 from Hikami-Larkin-Nagaoka fitting of magnetoconductivity describe the quantum correction to conductivity. An anomalous temperature dependence of A1g Raman modes confirms enhanced electron-phonon interactions. Our results establish the involvement of vibrations of Bi-Te with existence of topological surface states and WAL in Bi2GeTe4.

This paper introduces a new comparison base stable sorting algorithm, named RS sort. RS Sort involves only the comparison of pair of elements in an array which ultimately sorts the array and does not involve the comparison of each element with every other element. RS sort tries to build upon the relationship established between the elements in each pass. Suppose there is an array containing three elements a1, a2, a3 and if a relationship exist such that a1

The present paper gives a statistical adventure towards exploring the average case complexity behavior of computer algorithms. Rather than following the traditional count based analytical (pen and paper) approach, we instead talk in terms of the weight based analysis that permits mixing of distinct operations into a conceptual bound called the statistical bound and its empirical estimate, the so called "empirical O". Based on careful analysis of the results obtained, we have introduced two new conjectures in the domain of algorithmic analysis. The analytical way of average case analysis falls flat when it comes to a data model for which the expectation does not exist (e.g. Cauchy distribution for continuous input data and certain discrete distribution inputs as those studied in the paper). The empirical side of our approach, with a thrust in computer experiments and applied statistics in its paradigm, lends a helping hand by complimenting and supplementing its theoretical counterpart. Computer science is or at least has aspects of an experimental science as well, and hence hopefully, our statistical findings will be equally recognized among theoretical scientists as well.

In this paper we present an adaptable fast matrix multiplication (AFMM) algorithm, for two nxn dense matrices which computes the product matrix with average complexity Tavg(n) = d1d2n3 with the acknowledgement that the average count is obtained for addition as the basic operation rather than multiplication which is probably the unquestionable choice for basic operation in existing matrix multiplication algorithms., Comment: No of tables is 1. No of diagrams is 01

Smart Sort algorithm is a "smart" fusion of heap construction procedures (of Heap sort algorithm) into the conventional "Partition" function (of Quick sort algorithm) resulting in a robust version of Quick sort algorithm. We have also performed empirical analysis of average case behavior of our proposed algorithm along with the necessary theoretical analysis for best and worst cases. Its performance was checked against some standard probability distributions, both uniform and non-uniform, like Binomial, Poisson, Discrete & Continuous Uniform, Exponential, and Standard Normal. The analysis exhibited the desired robustness coupled with excellent performance of our algorithm. Although this paper assumes the static partition ratios, its dynamic version is expected to yield still better results.

The present paper makes a study on Partition sort algorithm for negative binomial inputs. Comparing the results with those for binomial inputs in our previous work, we find that this algorithm is sensitive to parameters of both distributions. But the main effects as well as the interaction effects involving these parameters and the input size are more significant for negative binomial case.

In our previous work there was some indication that Partition Sort could be having a more robust average case O(nlogn) complexity than the popular Quick Sort. In our first study in this paper, we reconfirm this through computer experiments for inputs from Cauchy distribution for which expectation theoretically does not exist. Additionally, the algorithm is found to be sensitive to parameters of the input probability distribution demanding further investigation on parameterized complexity. The results on this algorithm for Binomial inputs in our second study are very encouraging in that direction., Comment: 8 pages