Hasil untuk "cond-mat.mtrl-sci"

Swetha Pemma, Rebecca Janisch, Gerhard Dehm et al.

The migration of grain boundaries leads to grain growth in polycrystals and is one mechanism of grain-boundary-mediated plasticity, especially in nanocrystalline metals. This migration is due to the movement of dislocation-like defects, called disconnections, which couple to externally applied shear stresses. While this has been studied in detail in recent years, the active disconnection mode was typically associated with specific macroscopic grain boundary parameters. We know, however, that varying microscopic degrees of freedom can lead to different atomic structures without changing the macroscopic parameters. These structures can transition into each other and are called complexions. Here, we investigate $[11\overline{1}]$ symmetric tilt boundaries in fcc metals, where two complexions -- dubbed domino and pearl -- were observed before. We compare these two complexions for two different misorientations: In $\Sigma19$b $[11\overline{1}]$ $(178)$ boundaries, both complexions exhibit the same disconnection mode. The critical stress for nucleation and propagation of disconnections is nevertheless different for domino and pearl. At low temperatures, the Peierls-like barrier for disconnection propagation dominates, while at higher temperatures the nucleation is the limiting factor. For $Σ$7 $[11\overline{1}]$ $(145)$ boundaries, we observed a larger difference. The domino and pearl complexions migrate in different directions under the same boundary conditions. While both migration directions are possible crystallographically, an analysis of the complexions' structural motifs and the disconnection core structures reveals that the choice of disconnection mode and therefore migration direction is directly due to the atomic structure of the grain boundary.

L. Alekseeva, A. Nokhrin, A. Orlova et al.

NaRe$_2$(PO$_4$)$_3$ phosphate-based ceramic with the structure of kosnarite mineral was obtained by spark plasma sintering. Rhenium (Re) served as a chemical and structural analog of technetium. The ceramic relative density was 85%. The mechanism of Re static leaching from NaRe$_2$(PO$_4$)$_3$ ceramic at room temperature was investigated. The leaching rate of rhenium was $1.3\times10^{-5}$ g/(cm$^2$*day).

Jong Mok Ok, Narayan Mohanta, Jie Zhang et al.

Quantum materials (QMs) with strong correlation and non-trivial topology are indispensable to next-generation information and computing technologies. Exploitation of topological band structure is an ideal starting point to realize correlated topological QMs. Herein, we report that strain-induced symmetry modification in correlated oxide SrNbO3 thin films creates an emerging topological band structure. Dirac electrons in strained SrNbO3 films reveal ultra-high mobility (100,000 cm2/Vs), exceptionally small effective mass (0.04me), and non-zero Berry phase. More importantly, strained SrNbO3 films reach the extreme quantum limit, exhibiting a sign of fractional occupation of Landau levels and giant mass enhancement. Our results suggest that symmetry-modified SrNbO3 is a rare example of a correlated topological QM, in which strong correlation of Dirac electrons leads to the realization of fractional occupation of Landau levels.

Hisao Nakamura, Johannes Hofmann, Nobuki Inoue et al.

The interface between topological and normal insulators hosts metallic states that appear due to the change in band topology. While these topological states at a surface, i.e., a topological insulator-air/vacuum interface, have been studied intensely, topological states at a solid-solid interface have been less explored. Here we combine experiment and theory to study such \textit{embedded} topological states (ETSs) in heterostructures of GeTe (normal insulator) and Sb$_2$Te$_3$ (topological insulator). We analyse their dependence on the interface and their confinement characteristics. To characterise the heterostructures, we evaluate the GeTe-Sb$_2$Te$_3$ band offset using X-ray photoemission spectroscopy, and chart the elemental composition using atom probe tomography. We then use first-principles to independently calculate the band offset and also parametrise the band structure within a four-band continuum model. Our analysis reveals, strikingly, that under realistic conditions, the interfacial topological modes are delocalised over many lattice spacings. Interestingly, the first-principles calculations indicate that the ETSs are relatively robust to disorder and this may have practical ramifications. Our study provides insights into how to manipulate topological modes in heterostructures and also provides a basis for recent experimental findings [Nguyen \textit{et al.}, Sci. Rep. \textbf{6}, 27716 (2016)] where ETSs were seen to couple over large distances.

E. Butler, Kelly Greve

palsy. Phys Ther. 2010;90(2):269-279. 23. Verschuren O, Peterson MD, Balemans AC, Hurvitz EA. Exercise and physical activity recommendations for people with cerebral palsy. Dev Med Child Neurol. 2016;58(8):798-808. 24. Scholtes VA, Dallmeijer AJ, Rameckers EA, et al. Lower limb strength training in children with cerebral palsy—a randomized controlled trial protocol for functional strength training based on progressive resistance exercise principles. BMC Pediatr. 2008;8:41. 25. Boyd RN, Graham HK. Objective measurement of clinical findings in the use of botolinium toxin type A for the management of children with cerebral palsy. Eur J Neurol. 1999;6:23-35. 26. Hamid MSA, Ali MRM, Yusof A. Interrater and intrarater reliability of the active knee extension (AKE) test among healthy adults. J Phys Ther Sci. 2013;25:957-961. 27. McDowell BC, Hewitt V, Nurse A, Weston T, Baker R. The variability of goniometric measurements in ambulatory children with spastic cerebral palsy. Gait Posture. 2000;12(2):114-121. 28. McWhirk LB, Glanzman AM. Within-session inter-rater reliability of goniometric measures in patients with spastic cerebral palsy. Pediatr Phys Ther. 2006;18(4):262-265. 29. Ten Berge SR, Halbertsma JP, Maathuis PG, Verheij NP, Dijkstra PU, Maathuis KG. Reliability of popliteal angle measurement: a study in cerebral palsy patients and healthy controls. J Pediatr Orthop. 2007; 27(6):648-652. 30. Bennett DA. How can I deal with missing data in my study? Aust N Z J Public Health. 2001;25(5):464-469. 31. Terjesen T, Lofterod B, Skaaret I. Gait improvement surgery in ambulatory children with diplegic cerebral palsy. Acta Orthop. 2015;86(4):511517. 32. Faigenbaum AD, Kraemer WJ, Blimkie CJ, et al. Youth resistance training: updated position statement paper from the national strength and conditioning association. J Strength Cond Res. 2009;23(5 suppl): S60-S79. 33. Holm I, Fredriksen P, Fosdahl M, Vollestad N. A normative sample of isotonic and isokinetic muscle strength measurements in children 7 to 12 years of age. Acta Paediatr. 2008;97(5):602607.

Sean Knight, Alyssa Mock, Rafał Korlacki et al.

The isotropic average conduction band minimum electron effective mass in Sn-doped monoclinic single crystal $β$-Ga$_2$O$_3$ is experimentally determined by mid-infrared optical Hall effect to be $(0.284\pm0.013)m_{0}$ combining investigations on ($010$) and ($\bar{2}01$) surface cuts. This result falls within the broad range of values predicted by theoretical calculations for undoped $β$-Ga$_2$O$_3$. The result is also comparable to recent density functional calculations using the Gaussian-attenuation-Perdue-Burke-Ernzerhof hybrid density functional, which predict an average effective mass of $0.267m_{0}$ (arXiv:1704.06711 [cond-mat.mtrl-sci]). Within our uncertainty limits we detect no anisotropy for the electron effective mass, which is consistent with most previous theoretical calculations. We discuss upper limits for possible anisotropy of the electron effective mass parameter from our experimental uncertainty limits, and we compare our findings with recent theoretical results.

Qiaolin Zhang, Hui Sun, S. Fan et al.

C. Foy

Masaki Kobayashi, Shinobu Ohya, Iriya Muneta et al.

Clarification of the position of the Fermi level ($E_\mathrm{F}$) is important in understanding the origin of ferromagnetism in the prototypical ferromagnetic semiconductor Ga$_{1-x}$Mn$_x$As (GaMnAs). In a recent publication, Souma $et$ $al$. [Sci. Rep. $\mathbf{6}$, 27266 (2016)], have investigated the band structure and the $E_\mathrm{F}$ position of GaMnAs using angle-resolved photoemission spectroscopy (ARPES), and concluded that $E_\mathrm{F}$ is located in the valence band (VB). However, this conclusion contradicts a number of recent experimental results for GaMnAs, which showed that $E_\mathrm{F}$ is located above the VB maximum in the impurity band (IB). Here, we show an alternative interpretation of their ARPES experiments, which is consistent with those recent experiments and supports the picture that $E_\mathrm{F}$ is located above the VB maximum in the IB.

S. Souma, L. Chen, R. Oszwałdowski et al.

Recently, Kobayashi et al. (arXiv:1608.07718; ref. 1) have proposed an alternative interpretation of our angle-resolved photoemission spectroscopy (ARPES) results for the dilute ferromagnetic semiconductor (Ga,Mn)As. They claim that our ARPES data [Sci. Rep. 6, 27266 (2016); ref. 2] can be explained by locating the Fermi level EF above the valence-band top, supporting the impurity-band model of ferromagnetic (Ga,Mn)As. In this comment, we show that the assignment of bands' positions in respect to EF by Kobayashi et al. is not consistent with our data. By comparing the ARPES result to band-structure calculations, we demonstrate clearly that EF resides inside the valence band in accordance with the p-d Zener model.

Tricia A. Catalino, Kristen Johnson

M. Ahrend, P. Schneeweiss, U. Theobald et al.

Madhav P. Ghimire, R. K. Thapa, D. P. Rai et al.

First-principles density functional theory (DFT) is used to investigate the electronic and magnetic properties of Sr$_4$Rh$_3$O$_{10}$, a member of the Ruddlesden-Popper series. Based on the DFT calculations taking into account the co-operative effect of Coulomb interaction ($U$) and spin-orbit couplings (SOC), Sr$_4$Rh$_3$O$_{10}$ is found to be a half metallic ferromagnet (HMF) with total angular moment $μ_{\rm {tot}}$=12$μ_B$ per unit cell. The material has almost 100$\%$ spin-polarization at the Fermi level despite of sizable SOC. Replacement of Rh atom by the isovalent Co atom is considered. Upon full-replacement of Co, a low-spin to intermediate spin transition happens resulting in a HMF state with the total angular moment three-time larger (i.e. $μ_{\rm {tot}}$=36$μ_B$ per unit cell), compared to Sr$_4$Rh$_3$O$_{10}$. We propose Sr$_4$Rh$_3$O$_{10}$ and Sr$_4$Co$_3$O$_{10}$ as candidates of half metals.

Samuel Poncé, Gabriel Geadah-Antonius, P. Boulanger et al.

L. Dominguez, M. Barbagallo

4. Hartman J, Tang JE, Wilkinson SB, et al. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. Am J Clin Nutr 2007;86:373e381. 5. Josse AR, Tang JE, Tarnopolsky MA, et al. Body composition and strength changes in women with milk and resistance exercise. Med Sci Sports Exerc 2010;42:1122e1130. 6. Kerksick CM, Rasmussen CJ, Lancaster SL, et al. The effects of protein and amino acid supplementation on performance and training adaptations during ten weeks of resistance training. J Strength Cond Res 2006;20:643e653. 7. Ballard T, Specker B, Binkley T, et al. Effect of protein supplementation during a 6-month strength and conditioning program on areal and volumetric bone parameters. Bone 2006;38:898e904. 8. Bemben MG, Witten MS, Carter DL, et al. The effects of supplementation with creatine and protein on muscle strength following a traditional resistance training program in middle-aged and older men. J Nutr Health Aging 2010;14: 155e159. 9. Campbell W, Crim M, Young V, et al. Effects of resistance training and dietary protein intake on protein metabolism in older adults. Am J Physiol Endocrinol Metab 1995;268:E1143eE1153. 10. Rozenek R, Ward P, Long S, et al. Effects of high-calorie supplements on body composition and muscular strength following resistance training. J Sports Med Phys Fitness 2002;42:340e347. 11. Verdijk L, Jonkers R, Gleeson B, et al. Protein supplementation before and after exercise does not further augment skeletal muscle hypertrophy after resistance training in elderly men. Am J Clin Nutr 2009;89:608e616. 12. Walberg Rankin J, Goldman L, Puglisi M, et al. Effect of postexercise supplement consumption on adaptations to resistance training. J Am Coll Nutr 2004; 23:322e330. 13. Cermak N, Res P, de Groot L, et al. Protein supplementation augments the skeletal muscle adaptive response to resistance-type exercise training: A metaanalysis. Am J Clin Nutr 2012;96:1454e1464. 14. Tieland M, Dirks ML, van der Zwaluw N, et al. Protein supplementation increases muscle mass gain during prolonged resistance-type exercise in frail eldelry people: A randomized double-blind, placebo-controlled trial. J Am Med Dir Assoc 2012;13:713e719. 15. Leenders M, Verdijk L, Hoeven L, et al. Protein supplementation during resistance-type exercise training in the elderly. Med Sci Sports Exerc; 2012. Sept 10 Epub ahead of print. 16. Peterson M, Sen A, Gordon P. Influence of resistance exercise on lean body mass in aging adults: A meta-analysis. Med Sci Sports Exerc 2011;43:249e258. 17. Tieland M, van de Rest O, Dirks ML, et al. Protein supplementation improves physical performance in frail elderly people: A randomized, double-blind, placebo-controlled trial. J Am Med Dir Assoc 2012;13:720e726.

Naoyuki Tateiwa, Yoshinori Haga, Tatsuma D Matsuda et al.

Two modifications have been made to a miniature ceramic anvil high pressure cell (mCAC) designed for magnetic measurements at pressures up to 12.6 GPa in a commercial superconducting quantum interference (SQUID) magnetometer [N. Tateiwa et al., Rev. Sci. Instrum. 82, 053906 (2011)., ibid. 83, 053906 (2012)]. Replacing the Cu-Be piston in the former mCAC with a composite piston composed of the Cu-Be and ceramic cylinders reduces the background magnetization significantly smaller at low temperatures, enabling more precise magnetic measurements at low temperatures. A second modification to the mCAC is the utilization of a ceramic anvil with a hollow in the center of the culet surface. High pressures up to 5 GPa were generated with the "cupped ceramic anvil" with the culet size of 1.0 mm.

S. Wimmer, D. Ködderitzsch, K. Chadova et al.

A first-principles description of the spin Nernst effect, denoting the occurrence of a transverse spin current due to a temperature gradient, is presented. The approach, based on an extension to the Kubo-Streda equation for spin transport, supplies in particular the formal basis for investigations of diluted as well as concentrated alloys. Results for corresponding applications to the alloy system Au-Cu give the intrinsic and extrinsic contributions to the relevant transport coefficients. Using scaling laws allows in addition to split the extrinsic contribution into its skew scattering and side-jump parts.

Christina Bjerkén, Ali R. Massih

The time-dependent Ginzburg-Landau (TDGL) equation for a single component non-conservative structural order parameter is used to study the spatio-temporal evolution of a second phase in the vicinity of an edge dislocation in an elastic crystalline solid. A symmetric Landau potential of sixth-order is employed. Dislocation field and elasticity modify the second-order and fourth-order coefficients of the Landau polynomial, respectively, where the former makes the coefficient singular at the origin. The TDGL equation is solved numerically using a finite volume method, where a wide range of parameter sets is explored. Computations are made for temperatures both above and below the transition temperature of a defect-free crystal Tc0. In both cases, the effects of the elastic properties of the solid and the strength of interaction between the order parameter and the elastic displacement field are examined. If the system is quenched below Tc0, steady state is first reached on the compressive side of the dislocation. On the tensile side, the growth is held back. The effect of thermal noise term in the TDGL equation is studied. We find that if the dislocation is introduced above Tc0, thermal noise supports the nucleation of the second phase, and steady state will be attained earlier than if the thermal noise were absent. For a dislocation-free solid, we have compared our numerical computations for a mean-field (spatially averaged) order parameter versus time with the late time growth of the ensemble-averaged order parameter, calculated analytically, and find that both results follow late time logistic curves.

S. C. Speller, T. B. Britton, G. M. Hughes et al.

The interplay between superconductivity, magnetism and crystal structure in iron-based superconductors is a topic of great interest amongst the condensed matter physics community as it is thought to be the key to understanding the mechanisms responsible for high temperature superconductivity. Alkali metal doped iron chalcogenide superconductors exhibit several unique characteristics which are not found in other iron-based superconducting materials such as antiferromagnetic ordering at room temperature, the presence of ordered iron vacancies and high resistivity normal state properties. Detailed microstructural analysis is essential in order to understand the origin of these unusual properties. Here we have used a range of complementary scanning electron microscope based techniques, including high-resolution electron backscatter di raction mapping, to assess local variations in composition and lattice parameter with high precision and sub-micron spatial resolution. Phase separation is observed in the Csx Fe2-ySe2 crystals, with the minor phase distributed in a plate-like morphology throughout the crystal. Our results are consistent with superconductivity occurring only in the minority phase.

K. Panasiewicz, W. Koziara, H. Sulewska et al.