Frequency-dependent Faraday and Kerr rotation in anisotropic nonsymmorphic Dirac semimetals in a magnetic field

We calculate the frequency-dependent longitudinal and Hall conductivities and the Faraday and Kerr rotation angles for a single sheet of anisotropic Dirac semimetal protected by nonsymmorphic symmetry in the presence of a perpendicular magnetic field. While the magnetic field causes a rotation of the plane of polarization of the light, the anisotropy causes the appearance of an elliptically polarized component in an initially linearly polarized beam. The two effects can be combined in a single complex Faraday rotation angle. At the zero-frequency limit, we find a finite value of the Faraday rotation angle, which is given by $2\alpha_F$, where $\alpha_F$ is the effective fine structure constant associated with the velocity of the linearly dispersing Dirac fermions. We also find a logarithmic enhancement of the Faraday (and Kerr) rotation angles as the frequency of the light approaches the absorption edge associated with the magnetic field-induced gap. While the enhancement is reduced by impurity scattering, it remains significant for an attainable level of material purity. These results indicate that two-dimensional Dirac materials protected by nonsymmorphic symmetry are responsive to weak magnetic fields and can be used as platforms for magneto-optic applications, such as the realization of polarization-rotating devices.Comment: 24 pages, 7 Figure

Exotic Superconducting Properties in Topological Nodal Semimetal PbTaSe2_2

We report the electronic properties of superconductivity in the topological nodal-line semimetal PbTaSe$_2$. Angle-resolved photoemission measurements accompanied by band calculations confirmed the nodal-line band structure in the normal state of single crystalline PbTaSe$_2$. Resistivity, magnetic-susceptibility and specific heat measurements have also been performed on high-quality single crystals. We observed upward features and large anisotropy in upper critical field ($H_{c2}$) measured in-plane (H//\textbf{ab}) and out-plane (H//\textbf{c}), respectively. Especially, $H_{c2}$ measured in H//\textbf{ab} shows sudden upward features rather than a signal of saturation in ultralow temperatures. The specific heat measurements under magnetic field reveal a full superconducting gap with no gapless nodes. These behaviors in this clean noncentrosymmetric superconductor is possibly related to the underlying exotic physics, providing important clue for realization of topological superconductivity.Comment: 6 pages, 5 figures,1 table;Accepted for publication on PR

Research on Warehouse Target Localization and Tracking Based on KF and WSN

Abstract: This paper firstly established the model of warehouse targeting and tracking system based on Wireless Sensor Networks (WSN). The principle of Location and tracking is based on the maximum likelihood estimation method of multilateral measurement. According to monitoring motion trajectory of the same unknown target node within a continuous period of time, the motion equation can be established. It can achieve the effective tracking of warehouse target that KF algorithm is applied to carrying out the state estimation of warehouse target motion equation. Simulation results show that, while the warehouse target tracking system state equations are linear, using KF algorithm can obtain satisfactory tracking accuracy. Copyright © 2014 IFSA Publishing, S. L