6 research outputs found
Study on Susceptibilities of Superconductors BaPtSb and BaPtAs with Honeycomb Structure
The low-energy electronic properties of the new superconductors BaPtSb and
BaPtAs with an ordered honeycomb network are investigated in the normal phase,
where the former compound is a candidate for time-reversal symmetry-breaking
superconductors. By means of the first-principles calculation, we show that
there exist two-dimensional cylinder-like Fermi surfaces around the kz axis and
one outer spherelike Fermi surface around the K and K' points in both
compounds, which are mainly composed of Pt 5d and Sb 5p/As 4p electrons. We
construct low-energy effective models, which are well described by using three
bands consisting of two Pt 5d orbitals and one Sb 5p/As 4p orbital. By
evaluating susceptibilities using effective models, we find that dominant
contributions to those susceptibilities result from the outer spherelike Fermi
surface. Whereas out-of-plane fluctuations are enhanced in both compounds in
the higher-temperature region, in-plane fluctuations become dominant in the
very low-temperature region in BaPtSb owing to a better nesting condition in
the k_z=0 plane from the outer spherelike Fermi surface. These fluctuations
yield instabilities to ordered states, such as superconductivity, and might be
associated with the occurrence of the superconducting state with time-reversal
symmetry breaking in BaPtSb.Comment: 7 pages, 9 figure
X-ray tomographic analysis of the initial structure of the royal chamber and the nest-founding behavior of the drywood termite Incisitermes minor
The nesting biology of the drywood termite, Incisitermes minor, is poorly understood. To date, no published data are available regarding the in situ nest-gallery development of I. minor. Three naturally infested Sitka spruce (Picea sitchensis Bong. Carriere) timbers were analyzed by X-ray computer tomography to observe the structure of the first royal chamber and the termiteās nest-founding behavior. One timber was infested by a group of termites which emerged from their natal nest. The other two timbers were infested by dealate reproductives from the nuptial flight. The study revealed that the drywood termite engages in outside foraging activity and has great foraging flexibility. Computer tomographic images also revealed that I. minor reproductives showed anatomical selectivity in their nest-founding activity. The structure of the initial royal chambers varied to follow the anatomical texture of the timbers, which resembled either a European pear shape or a cashew nut shape