Spin-dependent transport in all-carbon multifunctional spintronic device

By using density functional theory and non-equilibrium Green’s function method, we investigate the spin-dependent transport properties of an all-carbon spintronic device consisting of a perylene molecule linked to two symmetrical ferromagnetic zigzag-edge graphene nanoribbon (ZGNR) electrodes via carbon atomic chains, where the magnetization of ZGNR electrodes are modulated by applying an external magnetic field. The device exhibits spin filtering and negative differential resistance (NDR) effect in parallel spin configuration. Bipolar spin filtering, spin rectifying and NDR effect are revealed in antiparallel spin configuration. And there is a giant magnetoresistance effect between parallel and antiparallel spin configurations. We discuss these interesting transport mechanisms, and suggest that the proposed all-carbon device holds promise in high-performance multifunctional nanoelectronic devices

Switching behavior induced by different substituents of group in single molecular device

We investigate the electronic transport properties of photochromic azobenzene-based molecular devices with Au electrodes using non-equilibrium Green’s function and density functional theory. A reversible switching behavior between cis and trans isomerization is found in the device. In addition, the substituent of −NH2 on the right end hydrogen atom of azobenzene molecule reduces the switching ratio of current, consequently the disappearance of switching behavior, while the substituent of −NO2 improves the switching ratio of current. We discuss the different electronic transport induced by different substituents through the transmission spectra, localized density of states, molecular projected self-consistent Hamiltonian and transmission pathways. The observed polarization effect under bias is explained by the evolution of molecular projected self-consistent Hamiltonian of LUMO level. The results indicate that the electron-withdrawing group −NO2 substituting right terminal hydrogen of azobenzene molecule becomes a candidate for improving the performance of molecular device

Shell effect and capture cross sections in the synthesis of superheavy nuclei

The shell effect is included in the improved isospin dependent quantum molecular dynamics model in which the shell correction energy of the system is calculated by using the deformed two-center shell model. A switch function is introduced to connect the shell correction energy of the projectile and the target with that of the compound nucleus during the dynamical fusion process. It is found that the calculated capture cross sections reproduce the experimental data quantitatively at the energy near the Coulomb barrier. The capture cross sections for reaction (35) (80) Br + (82) (208) Pb -> (117) (288) X are also calculated and discussed.National Natural Science Foundation of China 10575012 10435020 Doctoral Station Foundation of Ministry of Education of China 20080027001

Signature of local stress states in the deformation behavior of metallic glasses

The design of ductile heterogeneous metallic glasses (MGs) with enhanced deformability by purposely controlling theshear-band dynamics via modulation of the atomic-scale structures and local stress states remains a significantchallenge. Here, we correlate the changes in the local atomic structure when cooling to cryogenic temperature withthe observed improved shear stability. The enhanced atomic-level structural and elastic heterogeneities related to thenonaffine thermal contraction of the short-range order (SRO) and medium-range order (MRO) change thecharacteristics of the activation process of the shear transformation zones (STZs). The experimental observationscorroborated by Eshelby inclusion analysis and molecular dynamics simulations disclose the correlation between thestructuralfluctuations and the change in the stressfield around the STZ. The variations in the inclination axes of theSTZs alter their percolation mechanism, affect the shear-band dynamics and kinetics, and consequently delay shearfailure. These results expand the understanding of the correlation between the atomic-level structure and elementaryplastic events in monolithic MGs and thereby pave the way for the design of new ductile metallic alloys

Cryogenic-temperature-induced structural transformation of a metallic glass

The plasticity of metallic glasses depends largely on the atomic-scale structure. However, the details of the atomic-scale structure, which are responsible for their properties, remain to be clarified. In this study, in-situ high-energy synchrotron X-ray diffraction and strain-rate jump compression tests at different cryogenic temperatures were carried out. We show that the activation volume of flow units linearly depends on temperature in the non-serrated flow regime. A plausible atomic deformation mechanism is proposed, considering that the activated flow units mediating the plastic flow originate from the medium-range order and transit to the short-range order with decreasing temperature