Recent and forthcoming publications in pss

Momentum-space instantons and maximally localized flat-band topological Hamiltonians

Chao-Ming Jian, Zheng-Cheng Gu, and Xiao-Liang Qi

Materials with flat energy bands have interesting phases because of strong interaction effects. To find realistic Hamiltonians with flat bands, one wants to realize flat bands with local Hamiltonians. In this Letter, the authors show that the most localized flat-band Hamiltonians have eigenstate wavefunctions which are holomorphic functions in momentum space, and they correspond to instanton solutions in non-linear sigma models.

Part of Focus Issue on

Topological Insulators - From Materials Design to Reality

(Eds.: Claudia Felser, Shoucheng Zhang, Binghai Yan)

Phys. Status Solidi RRL (2012) DOI 10.1002/pssr.201206394

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Probing thermopower on the microscale

Pawel Ziolkowski, Gabriele Karpinski, Titas Dasgupta, and Eckhard Müller

Homogeneity analyses of thermoelectric (TE) semiconductors mainly require the determination of thermopower distribution, which provides meaningful information on the phase distribution and a benchmark on materials performance and repeatability of materials preparation. Insights into material structures and compositional distribution are not only necessary for investigations on high performance TE materials but are a fundamental pre-condition for the development of standard reference materials for thermopower. The high demand on their functional homogeneity disqualifies the use of high purity elements in most cases, as can be seen from the thermopower distribution of a germanium sample, since smallest impurities are frequently linked to a massive impact on thermopower due to its strong dependence on carrier concentration and structural variations.

Phys. Status Solidi A (2012) DOI 10.1002/pssa.201228512

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Crystallization kinetics and thermal stability in Ge-Sb-Se glasses

Wenhou Wei, Liang Fang, Xiang Shen, and Rongping Wang

The investigation on non-isothermal crystallization kinetics in Ge-Sb-Se glasses was performed by Wenhou Wei et al. using differential scanning calorimetry with five different heating rates of 7, 10, 14, 20, 30 K/min, respectively. Two different approaches, Kissinger's equation and the Matusita model, were employed to analyze kinetic crystallization. It is shown that the appropriate glass for application in photonics should have a composition with a mean coordination number of 2.4-2.5 where the glass exhibits a reasonably high glass transition temperature and low crystallization activation energy, as well as good thermal stability and strong glass forming ability.

Phys. Status Solidi B (2012) DOI 10.1002/pssb.201248284

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