Transport and Conductance in Fibonacci Graphene Superlattices with Electric and Magnetic Potentials

We investigate the electron transport and conductance properties in Fibonacci quasi-periodic graphene superlat- rices with electrostatic barriers and magnetic vector potentials. It is found that a new Dirac point appears in the band structure of graphene superlattice and the position of the Dirac point is exactly located at the energy corresponding to the zero-averaged w^ve number. The magnetic and eleetr/c potentials modify the energy band structure and transmission spectrum in entirely diverse ways. In addition, the angular-dependent transmission is blocked by the potential barriers at certain incident angles due to the appearance of the evanescent states. The effects of lattice constants and different potentials on angular-averaged conductance are also discussed.

INFLUENCE OF MAGNETIC FIELD ON ACCURACY OF ECM BY CHANGING THE CONDUCTIVITY OF ANODE FILM

The change of conductivity, thickness and scanning electron microscopy （SEM） appearance of the anode film of CrWMn in 10% NaNO3 at different anode potential either with or without the magnetic field applied are investigated by testing film resistance, galvanostatic transient and using SEM to design magnetic circuit in magnetic assisted electrochemical machining （MAECM）. The experiments show that the anode film has semi-conducting property. Compared with the situation without magnetic field applied, the resistance of the film formed at 1 .SV （anode potential） increased and decreased at 4.0V while B=0.4T and the magnetic north pole points toward anode. The SEM photo demonstrates that the magnetic field will densify the film in the passivation area and quicken dissolution of the anode metal in over-passivation area. Based on the influence of magnetic field on electrochemical machining（ECM） due to the changes of the anode film conductivity behavior, the magnetic north pole should be designed to point towards the workpiece surface that has been machined. Process experiments agree with the results of test analysis.

Pressure Tuning of Magnetism and Drastic Increment of Thermal Conductivity under Applied Magnetic Field in HgCr_2S_4

HgCr2S4 is a typical compound manifesting competing ferromagnetic （FM） and antiferromagnetic （AFM） exchanges as well as strong spin-lattice coupling. Here we study these effects by intentionally choosing a combination of magnetization under external hydrostatic pressure and thermal conductivity at various magnetic fields. Upon applying pressure up to 10 kbar at 1 kOe, while the magnitude of magnetization reduces progressively, the AFM ordering temperature TN enhances concomitantly at a rate of about 1.5 K/kbar. Strikingly, at lO kOe the field polarized FM state is found to be driven readily back to an AFM one even at only 5kbar. In addition, the thermal conductivity exhibits drastic increments at various fields in the temperature range with strong spin fluctuations, reaching about 30% at 50 kOe. Consequently, the results give new experimental evidence of spin-lattice coupling. Apart from the colossal magnetoeapacitance and colossal magnetoresistance reported previously, the findings here may enable new promising functionalities for potential applications.

Effects of(La,Sr) co-doping on electrical conduction and magnetic properties of BiFeO_3 nanoparticles

Multiferroic material as a photovoltaic material has gained considerable attention in recent years.Nanoparticles（NPs）La_（0.1）Bi_（0.9-x）Sr_xFeO_y（LBSF,x = 0,0.2,0.4） with dopant Sr^（2＋）ions were synthesized by the sol–gel method.A systematic change in the crystal structure from rhombohedral to tetragonal upon increasing Sr doping was observed.There is an obvious change in the particle size from 180 nm to 50 nm with increasing Sr substitution into LBFO.It was found that Sr doping effectively narrows the band gap from～2.08 e V to～1.94 e V,while it leads to an apparent enhancement in the electrical conductivity of LBSF NPs,making a transition from insulator to semiconductor.This suggests an effective way to modulate the conductivity of BiFeO_（3-）based multiferroic materials with pure phase by co-doping with La and Sr at the A sites of BiFeO_3.

Design Evolution and Analysis of the ITER Cryostat Support System

The cryostat is a vacuum tight container enveloping the entire basic systems of the ITER tokamak machine,including a vacuum vessel,a superconducting magnet and thermal shield etc.It is evacuated to a pressure of 10^-4Pa to limit the heat transfer via gas conduction and convection to the cryogenically cooled components.Another important function of cryostat is to support all the loads from the tokamak to the concrete floor of the pit by its support system during different operational regimes and accident scenarios.This paper briefly presents the design evolution and associated analysis of the cryostat support system and the structural interface with the building.

Design and implement of the signal generator in the magnetic focused conductivity tomography system

To improve stability and performance of the signal source and sweeping detection,as well as to extract abundant and reliable signal,the direct digital synthesis technology was employed to design the generator of the source which formed sweeping frequencies of sine wave output from 1 to 20 MHz.The planar spiral coil was con-nected as an amplitude modulation circuit.The same coil adopted differential architecture for signal detection and extraction.The MC1595 was utilized to compose a phase detector in which difference of phases varies with the change of frequencies.A low pass filter was designed to filter the carry waves of the sweeping source.Thereby the system gained abundant data and its stability was improved.Further,the spatial resolution of the system was enhanced.All of the above favors the use of software in the magnetic focused conductivity tomography system(MFCT)to reconstruct the image of conductivity within the human body.

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.

Multi-Functional Nano-Sciences of Advanced Metal Complexes:Photo-Induced Switching between Single-Chain Quantum Magnet and Paramagnet,and Conducting Single-Molecule Quantum Magnets

1 Results In the fields of the molecule-based magnets,the quantum molecular magnets have been attracting much attention. While the bulk magnets or classic magnets are based on the 3D ferro- or ferrimagnetic interaction,the quantum molecular magnets are based on the double-well potential barrier defined with DS2,where D and S are uni-axial anisotropy and spin quantum number,respectively.Therefore,while the memory capacity of the bulk magnets such as floppy disc is 109 bits,the quantum magnets may have th...