We report the voltage regulation of electrodeposited elliptical magnetostrictive Ni nanodot arrays from single-domain to nonvolatile vortex state at room temperature. On the piezoelectric substrate, isolated elliptical Ni nanodots are fabricated between a pair of square electrodes, with the long axis parallel to the joint line of the electrodes. By applying a voltage to the surface electrodes pair, local stress is generated to induce the magnetization of the nanodots from single-domain to vortex state. The magnetization state of the nanodots is characterized by a magnetic force microscope. Even after the voltage is removed or applying another voltage, the nanodots maintain a stable vortex magnetization state, which shows that the vortex state after regulation is nonvolatile. These results are of great significance for the study of the low-energy-consumption regulation of the nano-dimensional magnetic material and vortex state-based nonvolatile memory.

Based on the remarkable properties and the extraordinary performance in theory, carbon nanotube (CNT) has been attracted numerous of attention and research interest since it has been found from 1991. However, until now there are no mature applications in our daily life, because of its singularity properties (even in one single tube) and nano-scale size (hard to handle). In this study, the unique dispersion and filtration process were introduced to form a bulk material, so called buckypaper (BP), from few grams of CNTs. That causes the superior nature of CNTs could expand and homogenize from a nano scale to macro scale. And, make a great breakthrough for real application of CNTs.In the preliminary measurements the results show that (1) no matter SWCNTs-BP or MWCNTs-BP, under the low temperature of I-V test, all behave as a negative temperature coefficient of material and with a singularity temperature of resistivity around 150 K. (2) The four points test, in the room temperature, shows that the resistivity of BP fall into the range of 10-4 m, it s in the semimetal rank. It is strong support from (1) and (2) to know that BP is a semiconductor and with excellent conductivity property. In addition, BP also could be remodified its electrical characteristic by means of micro-coating with metal or metal oxides. The photoconductivity and photo voltage test radiated by different wavelengths of visible light were conducted in this study with the samples of stacking BP which include before and after modified. The results show that (1) there was no obviousreactions be observed on the samples of pristine BP stacking. (2) The reactions of those samples stacking with modified BP, especially coating with Ti or Zn, go up quite substantially. For example with the conduction of applied bias current of 0.1 mA, the stacking of Ti-SWCNTs-BP and Zn-MWCNTs-BP could get the photo voltage of 20 V under the stimulating of 23 mW, 940 nm IR, 0.4 mV under the stimulating of 48 mW, 470 nm blue light and 28 V under the stimulating of 23 mW, 405 nm UV. And, a maximum photo voltage of 6 V could be observed under the stimulating of blue light with no any of applied bias current.It overcomes the CNTs application bottleneck with BP material in this study, and re-modified its electrical characteristic by means of micro-coating with metal or metal oxides. It presumed that schottky barrier and dember effect play important role in the whole stacking sample, and could transfer the vibration effect under IR stimulating to the photoelectric effect under blue light stimulating. This shows a powerful evidence of CNTs as a prospect candidate for applications on photoelectric devices.Keywords-multi-walled carbon nanotube (MWCNTs), singlewalled carbon nanotubes (SWCNTs), buckypaper (BP), photoconductivity, photo voltage, photo detector.