Community Graph Sequence with Sequence Data of Network Structured Data

Recently, there has been increasing interest in data analysis for network structured data. The network structured data is represented the relation between one data and other data by graph structure. There are many network structured data such as social networks, biological networks in the real world. In this study, we will analysis the network structured data that has dynamic relation and complex interact with each data. And, we will approach the problem that is to extract transition pattern from the history of temporal change in their network structured data. Especially, in this paper, we will apply community graph sequences to graph sequences of network structured data that has large-scale and complex changes, and propose the method of extracting transition pattern of network structured data. We used social bookmark data as the data streams of analysis object and verified that social bookmark data is the network structured data that has large-scale and complex change

Boundary Scattering in Ballistic Graphene

We report magnetotransport measurements in ballistic graphene/hexagonal boron nitride mesoscopic wires where the charge carrier mean free path is comparable to wire width $W$. Magnetoresistance curves show characteristic peak structures where the peak field scales with the ratio of cyclotron radius $R_\textrm{c}$ and wire width $W$ as $W/R_\textrm{c} = 0.9 \pm 0.1$, due to diffusive boundary scattering. The obtained proportionality constant between $R_\textrm{c}$ and $W$ differs from that of a classical semiconductor 2D electron system where $W/R_\textrm{c} = 0.55$.Comment: 14 pages, 4 figure

グラフェンへの電気的スピン注入技術の確立

学位の種別:課程博士University of Tokyo(東京大学

Electric spectroscopy of vortex states and dynamics in magnetic disks

Spin-polarized radio frequency (RF) currents and RF-Oersted fields resonantly excite a magnetic vortex core confined in a micron-scale soft magnetic disk. In this study, we measured the rectifying voltage spectra caused by the anisotropic magnetoresistance oscillation due to the gyration of the vortex with different polarity and chirality. The measured spectra are presented such that we can determine the vortex properties and strength of the spin torques and Oersted field accurately and directly through analytical calculation.Comment: 39 pages,1 table, 10 figure