Researches into the Proton Conductivity of Molybdovanadophosphoric Acids with Wells－Dawson Structure

Five kinds of molybdovanadophosphoric acids H_7[P_2Mo_(17)VO_(62)],H_8[P_2Mo_(16)·V_2O_(62)],H_9 [P_2Mo_(15)V_3O_(62)],H_8[P_2Mo_(14)V_4O_(61)(H_2O)]and H_9[P_2Mo_(13)V_5O_(61)(H_2O)]have been synthesized.Their protop conductivities(C) have been measured.The effects of three main factors (frequency,hydration numbers,temperature)on the conductivity have been investigated.In some degree,heteropoly compounds with different structures give a different conductivity.

Enhancement of subgap conductance in a graphene superconductor junction by valley polarization

We theoretically study the differential conductance of a graphene/graphene superconductor junction, where the valley polarization of Dirac electrons is considered in the nonsuperconducting region. It is shown that the subgap conductance will increase monotonically with the valley-polarization strength when the chemical potential μ is near the Dirac point μ≤ 3？（？ is the superconducting gap）, whereas it will decrease monotonically when μ is far away from the Dirac point, μ≥ 5？.The former case is induced by the specular Andreev reflection while the retro-reflection accounts for the later result. Our findings may shed light on the control of conductance of a graphene superconductor junction by valley polarization.

Transmission Modulated by QuantumGatein AharonovCasher Ring

We study the electron transmission tuned by quantum gate in an Aharonov Casher (AC) ring. Transmission probability is obtained as a function of the normalized textured electric fields and Fermi energy. We find that modulating electron wavefunction in the stub can drastically affects electron transmission through the ring system. As Fermi energy crosses every eigenenergy of the isolated stub, the phases of both anomalous and periodic oscillations of the AC conductance generally have abrupt change by π. On two sides of several special Fermi energies, both anomalous and periodic oscillations have no abrupt phase change and are in phase. The detailed characteristics of the anomalous oscillations are dependent on the difference between the tilt angle of the spin and that of textured electric field. By modulating external magnetic field applied to the stub, we present AC oscillations of spin polarized conductance within adiabatic limit.

Polarized Conductance Oscillations Controlled by Magnetic Field in an Aharonov-Bohm Ring

Oscillations of the spin polarized conductance controlled by a uniform magnetic field in a modified Aharonov Bohm ring is studied with use of one dimensional quantum wave guide. Its expression at zero temperature is obtained as a function of the flux penetrating the ring and the magnetic field. It has been found that there are two kinds of polarized conductance extremas for a given Fermi energy. As Zeemann energy of spin polarized electron in the stub is varied, one kind of extrema exhibits continuous phase shift. However, another is locked at particular values of phase shift and it can only change abruptly from a maxima to a minima when Zeemann crosses the level of the bound state of isolated stub. This is a different mehanism for abrupt change phase of conductance osillations.

Hierarchical engineering of CoNi@Air@C/SiO_(2)@Polypyrrole multicomponent nanocubes to improve the dielectric loss capability and magnetic-dielectric synergy

Impedance matching characteristics and loss capabilities including magnetic loss,polarization loss and conduction loss are critical factors to improve microwave absorption performances(MAPs).To elevate these aspects,herein,yolk-shell structured CoNi@Air@C/SiO_(2)@Polypyrrole(PPy)magnetic multicomponent nanocubes(MCNCs)were designed and successfully fabricated in high efficiency through a continuous co-precipitation route,classical Stöber method,thermal treatment and polymerization reaction.The obtained results indicated that the formation of SiO_(2) effectively stabilized the cubic geometrical morphology and yolk-shell structure during the high-temperature pyrolysis process.The introduction of PPy greatly boosted their polarization loss and conductive loss capabilities.Therefore,the as-prepared yolkshell structured CoNi@Air@C/SiO_(2)@PPy MCNCs presented superior MAPs compared to CoNi@Air@C/SiO_(2) MCNCs.Furthermore,by regulating the content of PPy,the obtained CoNi@Air@C/SiO_(2)@PPy MCNCs displayed tunable and excellent comprehensive MAPs in terms of strong absorption capabilities,broad frequency bandwidths and thin matching thicknesses,which could be ascribed to the unique structure and excellent magnetic-dielectric synergistic effect.Therefore,our findings provided an alternative pathway to effectively utilize the magnetic-dielectric synergy and loss capabilities for the developing yolk-shell structured magnetic MCNCs as the strong wideband microwave absorbers.

Layered material GeSe and vertical GeSe/MoS2 p-n heterojunctions

GroupqV monochalcogenides are emerging as a new class of layered materials beyond graphene, transition metal dichalcogenides （TMDCs）, and black phosphorus （BP）. In this paper, we report experimental and theoretical investigations of the band structure and transport properties of GeSe and its heterostructures. We find that GeSe exhibits a markedly anisotropic electronic transport, with maximum conductance along the armchair direction. Density functional theory calculations reveal that the effective mass is 2.7 times larger along the zigzag direction than the armchair direction; this mass anisotropy explains the observed anisotropic conductance. The crystallographic orientation of GeSe is confirmed by angle- resolved polarized Raman measurements, which are further supported by calculated Raman tensors for the orthorhombic structure. Novel GeSeflVIoS2 p-n heterojunctions are fabricated, combining the natural p-type doping in GeSe and n-type doping in MoS2. The temperature dependence of the measured junction current reveals that GeSe and MoS2 have a type-II band alignment with a conduction band offset of N 0.234 eV. The anisotropic conductance of GeSe may enable the development of new electronic and optoelectronic devices, such as high-efficiency thermoelectric devices and plasmonic devices with resonance frequency continuously tunable through light polarization direction. The unique GeSe/MoS2 p-n junctions with type-II alignment may become essential building blocks of vertical tunneling field-effect transistors for low-power applications. The novel p-type layered material GeSe can also be combined with n-type TMDCs to form heterogeneous complementary metal oxide semiconductor （CMOS） circuits.

Magnetic field effects in organic light-emitting diodes with Co electrode

Tris-（8-hydroxyquinoline）-aluminum eAlq3T–based organic light-emitting diodes with Co electrode are fabricated. The positive magnetic electroluminescence（MEL） and magnetic conductance（MC） are observed in the samples, reaching 4.35% and 1.67% under the field of 42 m T at 50 K, respectively, and the MEL and MC traces can be fitted to non-Lorentzian line shapes. The MEL varies as a function of the Co thickness and reaches the optimal value at 10 nm. The MEL and MC dependence on voltage and temperature is also investigated. The electron-hole pair model and the spin-polarized injection mechanism are used to understand the experimental results.