Zhang, BoLiu, HongliZhao, WeiGuo, Zhengang...
7页查看更多>>摘要：Evolutionary algorithms and the particle swarm optimization method have been used to predict stable and metastable Cu structures between 0 and 2000 GPa that have not been discussed in previous studies, Cmcm phase is identified to be the most energetically competitive candidate. Density functional theory calculations illustrate that face-centered Cu atoms in (0 1 0), (0 1( -) 0) and (1 1 0) move along the 0 0 1 under the ultrahigh-pressure during the phase transformation from FCC (ambient pressure) to Cmcm (2000 GPa) structure. Phonon calculation further confirms the dynamical stability of this predicted structure, and the temperature dependence of electrical resistivity for Cmcm Cu will get reduced, predicted by phonon hardening with increasing pressure. The high-pressure structure still exhibits metallic behavior due to the finite electron DOS at the Fermi level, and the calculated elastic properties display superior bulk and shear modulus of Cmcm Cu with dramatic increase at 2000 GPa.
原文链接:
NSTL
Elsevier
Amaladass, E. P.Abhirami, S.Arasu, A. V. ThanikaiBaskaran, R....
7页查看更多>>摘要：The proximity-induced changes in magneto-transport properties of a topological insulator and a superconductor in an NbN/Bi1.95Sb0.05Se3 heterostructure are reported. Mechanically exfoliated single-crystal flake of Bi1.95Sb0.05Se3 topological insulator (TI) is partially covered with a similar to 150 nm thick niobium nitride superconductor using DC magnetron sputtering. The temperature-dependent resistance, R(T) across the junction, shows double transitions at 11.5 K and 8 K, followed by the resistance upturn. MR on NbN covered region exhibit the typical BC2 behavior. At T < 20 K, the uncovered TI part exhibits weak anti-localization (WAL) for B < +/- 1 T and a transition to negative MR at B > +/- 3.5 T, while the junction shows only the WAL feature. As the temperature increases, the classical B2 dependence is retrieved on the TI and across the junction. The temperature coefficient of the phase coherence length obtained from the Hikami Larkin Nagaoka (HLN) analysis changes sign at the superconducting transition TC, evincing the de-phasing of the quantum coherence WAL phenomenon by the proximity of a superconductor. In contrast, the BC2 behavior of the superconductor is less affected by TI.
原文链接:- NSTL
- Elsevier
Queiroz, J. C. A.Naeem, M.Sousa, I. A.Liborio, M. S....
11页查看更多>>摘要：Transparent conducting oxides (TCO), including ZnO/Zn2TiO4/ZnAl2O4 composite films, are of considerable importance in optoelectronic applications. We fabricated composite film assisted with DC magnetron sputtering using ceramic target material (ZnO, TiO2, and Al2O3 powders mixture). The influence of processing gases composition (0-50% O-2-Ar) on film characteristics, including structural, optical, and electronic properties, is assessed. All films contain hexagonal wurtzite ZnO structure and ZnAl2O4, Zn2TiO4 spinel phases, with (002), (100), and (101) as dominant orientation by increasing oxygen contents. The transmittance of deposited films is above 81% (except for 50% oxygen), and the bandgap lies between 3.73 and 3.28 eV (reduced by oxygen addition). The carrier concentration and mobility increase with oxygen addition up to 25%, and resistivity de-creases by increasing oxygen contents. This study shows that using ceramic targets, the compound film with variable composition, structural and optoelectronic properties can be obtained by altering the gases admixture.
原文链接:- NSTL
- Elsevier
