14,739 research outputs found

    The effect of asymmetry of the coil block on self-assembly in ABC coil-rod-coil triblock copolymers

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    Using the self-consistent field approach, the effect of asymmetry of the coil block on the microphase separation is focused in ABC coil-rod-coil triblock copolymers. For different fractions of the rod block fBf_{\text B}, some stable structures are observed, i.e., lamellae, cylinders, gyroid, and core-shell hexagonal lattice, and the phase diagrams are constructed. The calculated results show that the effect of the coil block fraction fAf_{\text A} is dependent on fBf_{\text B}. When fB=0.2f_{\text B}=0.2, the effect of asymmetry of the coil block is similar to that of the ABC flexible triblock copolymers; When fB=0.4f_{\text B}=0.4, the self-assembly of ABC coil-rod-coil triblock copolymers behaves like rod-coil diblock copolymers under some condition. When fBf_{\text B} continues to increase, the effect of asymmetry of the coil block reduces. For fB=0.4f_{\text B}=0.4, under the symmetrical and rather asymmetrical conditions, an increase in the interaction parameter between different components leads to different transitions between cylinders and lamellae. The results indicate some remarkable effect of the chain architecture on self-assembly, and can provide the guidance for the design and synthesis of copolymer materials.Comment: 9 pages, 3 figure

    New transformation of Wigner operator in phase space quantum mechanics for the two-mode entangled case

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    As a natural extension of Fan's paper (arXiv: 0903.1769vl [quant-ph]) by employing the formula of operators' Weyl ordering expansion and the bipartite entangled state representation we find new two-fold complex integration transformation about the Wigner operator (in its entangled form) in phase space quantum mechanics and its inverse transformation. In this way, some operator ordering problems can be solved and the contents of phase space quantum mechanics can be enriched.Comment: 8 pages, 0 figure

    Weyl superconductors

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    We study the physics of the superconducting variant of Weyl semimetals, which may be realized in multilayer structures comprising topological insulators and superconductors. We show how superconductivity can split each Weyl node into two. The resulting Bogoliubov Weyl nodes can be pairwise independently controlled, allowing to access a set of phases characterized by different numbers of bulk Bogoliubov Weyl nodes and chiral Majorana surface modes. We analyze the physics of vortices in such systems, which trap zero energy Majorana modes only under certain conditions. We finally comment on possible experimental probes, thereby also exploiting the similarities between Weyl superconductors and 2-dimensional p + ip superconductors.Comment: 13 pages, 5 figure

    Dual Fermion Method for Disordered Electronic Systems

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    While the coherent potential approximation (CPA) is the prevalent method for the study of disordered electronic systems, it fails to capture non-local correlations and Anderson localization. To incorporate such effects, we extend the dual fermion approach to disordered non-interacting systems using the replica method. Results for single- and two- particle quantities show good agreement with cluster extensions of the CPA; moreover, weak localization is captured. As a natural extension of the CPA, our method presents an alternative to the existing cluster theories. It can be used in various applications, including the study of disordered interacting systems, or for the description of non-local effects in electronic structure calculations.Comment: 5 pages, 4 figure

    Lambda and Anti-Lambda Hypernuclei in Relativistic Mean-field Theory

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    Several aspects about Λ\Lambda-hypernuclei in the relativistic mean field theory, including the effective Λ\Lambda-nucleon coupling strengths based on the successful effective nucleon-nucleon interaction PK1, hypernuclear magnetic moment and Λˉ\bar\Lambda-hypernuclei, have been presented. The effect of tensor coupling in Λ\Lambda-hypernuclei and the impurity effect of Λˉ\bar\Lambda to nuclear structure have been discussed in detail.Comment: 8 pages, 2 figures, Proceedings of the Sendai International Symposium "Strangeness in Nuclear and Hadronic Systems SENDAI08

    Enhanced spin-orbit torques in MnAl/Ta films with improving chemical ordering

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    We report the enhancement of spin-orbit torques in MnAl/Ta films with improving chemical ordering through annealing. The switching current density is increased due to enhanced saturation magnetization MS and effective anisotropy field HK after annealing. Both damplinglike effective field HD and fieldlike effective field HF have been increased in the temperature range of 50 to 300 K. HD varies inversely with MS in both of the films, while the HF becomes liner dependent on 1/MS in the annealed film. We infer that the improved chemical ordering has enhanced the interfacial spin transparency and the transmitting of the spin current in MnAl layer