Engineering planar transverse domain walls in biaxial magnetic nanostrips by tailoring transverse magnetic fields with uniform orientation

Designing and realizing various magnetization textures in magnetic nanostructures are essential for developing novel magnetic nanodevices in modern information industry. Among all these textures, planar transverse domain walls (pTDWs) are the simplest and the most basic, which make them popular in device physics. In this work, we report the engineering of pTDWs with arbitrary tilting attitude in biaxial magnetic nanostrips by transverse magnetic field profiles with uniform orientation but tunable strength distribution. Both statics and axial-field-driven dynamics of these pTDWs are analytically investigated. It turns out that for statics these pTDWs are robust again disturbances which are not too abrupt, while for dynamics it can be tailored to acquire higher velocity than Walker's ansatz predicts. These results should provide inspirations for designing magnetic nanodevices with novel one-dimensional magnetization textures, such as 360$^\circ$ walls, or even two-dimensional ones, for example vortices, skyrmions, etc.Comment: 14 pages, 3 figure

Conformal Ricci flow on asymptotically hyperbolic manifolds

In this article we study the short-time existence of conformal Ricci flow on asymptotically hyperbolic manifolds. We also prove a local Shi's type curvature derivative estimate for conformal Ricci flow.Comment: 19 pages. No figur

Surface and Edge States in Topological Semi-metals

We study the topologically non-trivial semi-metals by means of the 6-band Kane model. Existence of surface states is explicitly demonstrated by calculating the LDOS on the material surface. In the strain free condition, surface states are divided into two parts in the energy spectrum, one part is in the direct gap, the other part including the crossing point of surface state Dirac cone is submerged in the valence band. We also show how uni-axial strain induces an insulating band gap and raises the crossing point from the valence band into the band gap, making the system a true topological insulator. We predict existence of helical edge states and spin Hall effect in the thin film topological semi-metals, which could be tested with future experiment. Disorder is found to significantly enhance the spin Hall effect in the valence band of the thin films

An Empirical Analysis of Usability-Sociability Design for Sustaining Virtual Communities

This study aims to explore how the usability and sociability design of virtual communities could encourage members’ continuous participant in the communities. A theoretical model is proposed to explain the effects of usability and sociability design on continuous participation through members’ perceived usefulness, enjoyment and sense of belonging. Data is collected from members of five popular leisure oriented virtual communities in China. The results show that both perceived usefulness and enjoyment have impacts on members’ continuous participation intention. Among the usability and sociability design factors, we find that personalized service is the most critical mechanism that encourages members to continuously participate in virtual communities, while community infrastructure, friend connection and event organization also have positive effects on members’ continuous participation intention through individual motivations. However, it is surprised to find out that leaders’ involvement has no influence on members’ continuous participation intention. Both theoretical and practical implications of this study are discussed