Two-dimensional transition-metal halide CoBr3 with spin-polarized Dirac cone.

Recently, the discovery of two-dimensional transition-metal materials with non-trivial magnetic and electronic properties has spurred huge interest in investigating their applications in nanotechnology. Here, we report that the monolayer of CoBr3 possesses a quantum anomalous Hall insulating phase generated on the basis of first-principles calculations. We find that the CoBr3 monolayer is an intrinsic two-dimensional ferromagnetic material with a Curie temperature Tc = 264 K predicted from Monte Carlo simulations. The phonon spectra analysis indicates that the CoBr3 monolayer is dynamically stable. Taking into account spin-orbit coupling, this makes the electronic structure of the CoBr3 monolayer topologically non-trivial with a global band gap of 8.7 meV. The anomalous Hall conductivity calculation shows a Chern number C = 2, meaning the presence of a two edge state in nanoribbons of finite width. These findings not only add an experimentally feasible member to the quantum anomalous Hall insulator family, but also pave the way for highly promising application potentials in nanoelectronics and spintronics.

Scientific Collaboration in Chinese Nursing Research: A Social Network Analysis Study.

Collaboration has become very important in research and in technological progress. Coauthorship networks in different fields have been intensively studied as an important type of collaboration in recent years. Yet there are few published reports about collaboration in the field of nursing. This article aimed to reveal the status and identify the key features of collaboration in the field of nursing in China. Using data from the top 10 nursing journals in China from 2003 to 2013, we constructed a nursing scientific coauthorship network using social network analysis. We found that coauthorship was a common phenomenon in the Chinese nursing field. A coauthorship network with 228 subnetworks formed by 1428 nodes was constructed. The network was relatively loose, and most subnetworks were of small scales. Scholars from Shanghai and from military medical system were at the center of the Chinese nursing scientific coauthorship network. We identified the authors' positions and influences according to the research output and centralities of each author. We also analyzed the microstructure and the evolution over time of the maximum subnetwork.