Theory of Large Intrinsic Spin Hall Effect in Iridate Semimetals

We theoretically investigate the mechanism to generate large intrinsic spin Hall effect in iridates or more broadly in 5d transition metal oxides with strong spin-orbit coupling. We demonstrate such a possibility by taking the example of orthorhombic perovskite iridate with nonsymmorphic lattice symmetry, SrIrO3, which is a three-dimensional semimetal with nodal line spectrum. It is shown that large intrinsic spin Hall effect arises in this system via the spin-Berry curvature originating from the nearly degenerate electronic spectra surrounding the nodal line. This effect exists even when the nodal line is gently gapped out, due to the persistent nearly degenerate electronic structure. The magnitude of the spin Hall conductivity is shown to be comparable to the best known example such as doped topological insulators and the biggest in any transition metal oxides. To gain further insight, we compute the intrinsic spin Hall conductivity in both bulk and thin film systems. We find that the geometric confinement in thin films leads to significant modifications of the electronic states, leading to even bigger spin Hall conductivity in certain cases. We compare our findings with the recent experimental report on the discovery of large spin Hall effect in SrIrO3 thin films.11Ysciescopu

Comparison of selected canine vector-borne diseases between urban animal shelter and rural hunting dogs in Korea

A serological survey for Dirofilaria immitis, Anaplasma phagocytophilum, Ehrlichia canis, and Borrelia burgdorferi infections in rural hunting and urban shelter dogs mainly from southwestern regions of the Republic of Korea (South Korea) was conducted. From a total of 229 wild boar or pheasant hunting dogs, the number of serologically positive dogs for any of the four pathogens was 93 (40.6%). The highest prevalence observed was D. immitis (22.3%), followed by A. phagocytophilum (18.8%), E. canis (6.1%) and the lowest prevalence was B. burgdorferi (2.2%). In contrast, stray dogs found within the city limits of Gwangju showed seropositivity only to D. immitis (14.6%), and none of the 692 dogs responded positive for A. phagocytophilum, E. canis or B. burgdorferi antibodies. This study indicates that the risk of exposure to vector-borne diseases in rural hunting dogs can be quite high in Korea, while the urban environment may not be suitable for tick infestation on dogs, as evidenced by the low infection status of tick-borne pathogens in stray dogs

Fundamental Spin Interactions Underlying the Magnetic Anisotropy in the Kitaev Ferromagnet CrI3_3

We lay the foundation for determining the microscopic spin interactions in the two-dimensional (2D) ferromagnets by combining our angle-dependent ferromagnetic resonance (FMR) experiments on high quality CrI$_3$ single crystals with theoretical modeling based on symmetries. In the 2D limit, ferromagnetism is stabilized by magnetic anisotropy. We find the largest anisotropy arises from Kitaev interactions of strength $K~\sim-5.2$ meV, larger than the Heisenberg exchange $J~\sim-0.2$ meV. We further discover that the symmetric off-diagonal anisotropy $\Gamma\sim-67.5$ $\mu$eV, though small, plays the crucial role of opening a gap in the magnon spectrum and stabilizing ferromagnetism in the 2D limit. The resolution of the FMR data is sufficient to reveal a $\mu$eV-scale quadrupolar contribution in the $S=3/2$ magnet. Our identification of the interactions underlying ferromagnetism and exchange anisotropies opens paths towards 2D ferromagnets with higher T_\rm{C} and magnetically frustrated quantum spin liquids based on Kitaev physics.Comment: 5 pages, 4 figure

Topological and magnetic phases with strong spin-orbit coupling on the hyperhoneycomb lattice

We study the general phase diagram of correlated electrons for iridium-based (Ir) compounds on the hyperhoneycomb lattice, a crystal structure where the Ir4+ ions form a three-dimensional network with threefold coordination recently realized in the beta-Li2IrO3 compound. Using a combination of microscopic derivations, symmetry analysis, and density functional calculations, we determine the general model for the electrons occupying the j(eff) = 1/2 orbitals at the Ir4+ sites. In the noninteracting limit, we find that this model allows for both topological and trivial electronic band insulators along with metallic states. The effect of Hubbard-type electron-electron repulsion on the above electronic structure in stabilizing q = 0 magnetic order reveals a phase diagram with continuous phase transition between a topological band insulator and a Neel ordered magnetic insulator.close3

Ghost Hunter: a Handheld Augmented Reality Game System With Dynamic Environment

Abstract. The progress of handheld devices has encouraged many researchers to make efforts to use handheld devices as an augmented reality platform. However, one of the important problems is a lack of immersion and reality due to small display. To overcome this problem, we introduce dynamic environment which consists of some movable structures and their controller that enable changes of virtual world to affect the real world. It has an effect on expanding the user's view limited by the small display of the handheld device. We have also developed the game content, 'Ghost Hunter', which is suitable for this platform. keywords: handheld augmented reality, dynamic environment, entertainment syste

Ghost Hunter: a Handheld Augmented Reality Game System With Dynamic Environment

Abstract. The progress of handheld devices has encouraged many researchers to make efforts to use handheld devices as an augmented reality platform. However, one of the important problems is a lack of immersion and reality due to small display. To overcome this problem, we introduce dynamic environment which consists of some movable structures and their controller that enable changes of virtual world to affect the real world. It has an effect on expanding the user's view limited by the small display of the handheld device. We have also developed the game content, 'Ghost Hunter', which is suitable for this platform. keywords: handheld augmented reality, dynamic environment, entertainment syste