Wireless power transfer is expected in the use of an electric vehicle and a chip card. However, it requires a high efficiency and takes a long distance. In this paper, we propose the use of a magnetoplated wire (MPW), which is a copper wire (COW) whose circumference is plated with a magnetic thin film, to improve transmission efficiency. The MPW can reduce resistances due to the proximity effect comparison with the COW. The inner diameter of COW and MPW coils is d i = 37 mm and their number of turns is n = 10. As a result, the resistances of the COW and MPW at the frequency f = 12 MHz are 6.8  and 4.1 , respectively, which show a reduction of 40%. The quality factors of the COW and MPW at the frequency f = 12 MHz are 83 and 138, respectively, which show an increase of 66%. The efficiencies of the COW and MPW at a transmission distance of 10 mm are 69.8% and 77.7%, respectively, which show an increase of 7.9%.Index Terms-wireless power transfer, magnetic resonant coupling, efficiency, magnetoplated wire, litz wire, quality factor.

No abstract

Graphene was grown on both r-plane and c-plane sapphires by low-pressure chemical vapor deposition without using a metal catalyst. The growth pressure was systematically changed to investigate how the growth pressure effects the graphene growth. Consequently, it was found that the coverage of the graphene increased with increasing growth pressure on the r-plane sapphire while it decreased with increasing growth pressure on the c-plane sapphire. Raman spectroscopy and atomic force microscopy indicates that the growth layer is single-layer graphene on the r-plane sapphire while it is a bi-layer on the c-plane sapphire. Graphene is thought to grow on the r-plane sapphire simply in a two-dimensional nucleation mode. On the other hand, graphene tends to grow in the pits formed on the surface of the c-plane sapphire. The pits are thought to be produced by the oxygen desorption and have some catalytic effects.

No abstract

Abstract(Bi1−xLax)(Fe,Co)O3 multiferroic magnetic film were fabricated using pulsed DC (direct current) sputtering technique and demonstrated magnetization reversal by applied electric field. The fabricated (Bi0.41La0.59)(Fe0.75Co0.25)O3 films exhibited hysteresis curves of both ferromagnetic and ferroelectric behavior. The saturated magnetization (Ms) of the multiferroic film was about 70 emu/cm3. The squareness (S) (= remanent magnetization (Mr)/Ms) and coercivity (Hc) of perpendicular to film plane are 0.64 and 4.2 kOe which are larger compared with films in parallel to film plane of 0.5 and 2.5 kOe. The electric and magnetic domain structures of the (Bi0.41La0.59)(Fe0.75Co0.25)O3 film analyzed by electric force microscopy (EFM) and magnetic force microscopy (MFM) were clearly induced with submicron scale by applying a local electric field. This magnetization reversal indicates the future realization of high performance magnetic device with low power consumption.