Anomalous Nernst and Hall effects in magnetized platinum and palladium

We study the anomalous Nernst effect (ANE) and anomalous Hall effect (AHE) in proximity-induced ferromagnetic palladium and platinum which is widely used in spintronics, within the Berry phase formalism based on the relativistic band structure calculations. We find that both the anomalous Hall ($\sigma_{xy}^A$) and Nernst ($\alpha_{xy}^A$) conductivities can be related to the spin Hall conductivity ($\sigma_{xy}^S$) and band exchange-splitting ($\Delta_{ex}$) by relations $\sigma_{xy}^A =\Delta_{ex}\frac{e}{\hbar}\sigma_{xy}^S(E_F)'$ and $\alpha_{xy}^A = -\frac{\pi^2}{3}\frac{k_B^2T\Delta_{ex}}{\hbar}\sigma_{xy}^s(\mu)"$, respectively. In particular, these relations would predict that the $\sigma_{xy}^A$ in the magnetized Pt (Pd) would be positive (negative) since the $\sigma_{xy}^S(E_F)'$ is positive (negative). Furthermore, both $\sigma_{xy}^A$ and $\alpha_{xy}^A$ are approximately proportional to the induced spin magnetic moment ($m_s$) because the $\Delta_{ex}$ is a linear function of $m_s$. Using the reported $m_s$ in the magnetized Pt and Pd, we predict that the intrinsic anomalous Nernst conductivity (ANC) in the magnetic platinum and palladium would be gigantic, being up to ten times larger than, e.g., iron, while the intrinsic anomalous Hall conductivity (AHC) would also be significant.Comment: Accepted for publication in the Physical Review

Quasi-particle random phase approximation with quasi-particle-vibration coupling: application to the Gamow-Teller response of the superfluid nucleus 120^{120}Sn

We propose a self-consistent quasi-particle random phase approximation (QRPA) plus quasi-particle-vibration coupling (QPVC) model with Skyrme interactions to describe the width and the line shape of giant resonances in open-shell nuclei, in which the effect of superfluidity should be taken into account in both the ground state and the excited states. We apply the new model to the Gamow-Teller resonance in the superfluid nucleus $^{120}$Sn, including both the isoscalar spin-triplet and the isovector spin-singlet pairing interactions. The strength distribution in $^{120}$Sn is well reproduced and the underlying microscopic mechanisms, related to QPVC and also to isoscalar pairing, are analyzed in detail.Comment: 32 pages, 11 figures, 4 table

Topological Crystalline Insulator and Quantum Anomalous Hall States in IV-VI based Monolayers and their Quantum Wells

Different from the two-dimensional (2D) topological insulator, the 2D topological crystalline insulator (TCI) phase disappears when the mirror symmetry is broken, e.g., upon placing on a substrate. Here, based on a new family of 2D TCIs - SnTe and PbTe monolayers - we theoretically predict the realization of the quantum anomalous Hall effect with Chern number C = 2 even when the mirror symmetry is broken. Remarkably, we also demonstrate that the considered materials retain their large-gap topological properties in quantum well structures obtained by sandwiching the monolayers between NaCl layers. Our results demonstrate that the TCIs can serve as a seed for observing robust topologically non-trivial phases.Comment: 5 pages, submitted on 27th Feb 201

Incorporating the position of sharing action in predicting popular videos in online social networks

LNCS v.8787 entitled: Web Information Systems Engineering - WISE 2014: 15th International Conference, Thessaloniki, Greece, October 12-14, 2014, Proceedings, Part 2Predicting popular videos in online social networks (OSNs) is important for network traffic engineering and video recommendation. In order to avoid the difficulty of acquiring all OSN users’ activities, recent studies try to predict popular media contents in OSNs only based on a very small number of users, referred to as experts. However, these studies simply treat all users’ diffusion actions as the same. Based on large-scale video diffusion traces collected from a popular OSN, we analyze the positions of users’ video sharing actions in the propagation graph, and classify users’ video sharing actions into three different types, i.e., initiator actions, spreader actions and follower actions. Surprisingly, while existing studies mainly focus on the initiators, our empirical studies suggest that the spreaders actually play a more important role in the diffusion process of popular videos. Motivated by this finding, we account for the position information of sharing actions to select initiator experts, spreader experts and follower experts, based on corresponding sharing actions. We conduct experiments on the collected dataset to evaluate the performance of these three types of experts in predicting popular videos. The evaluation results demonstrate that the spreader experts can not only make more accurate predictions than initiator experts and follower experts, but also outperform the general experts selected by existing studies.postprin

Possible discovery of the r-process characteristics in the abundances of metal-rich barium stars

We study the abundance distributions of a sample of metal-rich barium stars provided by Pereira et al. (2011) to investigate the s- and r-process nucleosynthesis in the metal-rich environment. We compared the theoretical results predicted by a parametric model with the observed abundances of the metal-rich barium stars. We found that six barium stars have a significant r-process characteristic, and we divided the barium stars into two groups: the r-rich barium stars ($C_r>5.0$, [La/Nd]\,$<0$) and normal barium stars. The behavior of the r-rich barium stars seems more like that of the metal-poor r-rich and CEMP-r/s stars. We suggest that the most possible formation mechanism for these stars is the s-process pollution, although their abundance patterns can be fitted very well when the pre-enrichment hypothesis is included. The fact that we can not explain them well using the s-process nucleosynthesis alone may be due to our incomplete knowledge on the production of Nd, Eu, and other relevant elements by the s-process in metal-rich and super metal-rich environments (see details in Pereira et al. 2011).Comment: 5 pages, 5 figures, accepted for publication in A&

Characterization of volatiles Tribolium castaneum (H.) in flour using solid phase microextraction-gas chromatography mass spectrometry (SPME-GCMS)

The objective of this study was to identify volatile organic compounds (VOCs) from flour, Tribolium castaneum (Herbst) and flour infested by T. castaneum separately, to confirm the difference of healthy flour and flour infested by T. castaneum and to explore the new technique to diagnose stored flour's quality by its VOCs change. Headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS) were used to detect the VOCs of three different samples. Totally, 71 different compounds were identified in flour, T. castaneum and T. castaneum infested flour. Therefore, 27 VOCs were identified from flour alone, 32 VOCs from T. castaneum and 39 VOCs from T. castaneum infested flour. The compound 2-ethyl-2,5-cyclohexadiene-1,4-dione is only found in T. castaneum infested flour. This suggests that 2-ethyl-2,5-cyclohexadiene-1,4-dione can be a useful VOC for detecting T. castaneum in flour

Measurement-driven temporal analysis of information diffusion in online social networks

The rapid development of online social networks (OSN) renders them a popular mechanism for information diffusion. Studying the temporal characteristics is critical in understanding the diffusion process. However, due to the lack of well-defined propagation data, hardly any study addresses the temporal feature of information diffusion in OSN. In this paper, we present a measurement study on information diffusion in the Renren social network. We investigate the latency of information propagation along social links and define the 'activation time' for an OSN user, and find that the activation time follows the lognormal distribution. Based on this, we develop two new information diffusion models incorporating asynchronous activation times. Application of the models in the influence maximization problem shows that they capture the temporal diffusion behavior very well. This leads to fundamental ramifications to many related OSN applications. © 2012 IEEE.published_or_final_versio