Chu, J.-H. | Search NASA

DOE OSTI2019

Anisotropic Superconducting Gap in Optimally Doped Iron–Based Material

In this work we offer a comprehensive optical investigation of the optimally hole-doped Ba 0.6 K 0.4 Fe 2 As 2 over a broad spectral range, as a function of temperature and of tunable applied stress, which acts as an external symmetry breaking field. We show that there is a large electronic nematicity at optimal doping which extends right under the superconducting dome and implies an anisotropy of the superconducting energy gaps.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1976

Response of deep and shallow tropical maritime cumuli to large-scale processes

The bulk diagnostic method of Yanai et al. (1973) and a simplified version of the spectral diagnostic method of Nitta (1975) are used for a more quantitative evaluation of the response of various types of cumuliform clouds to large-scale processes, using the same data set in the Marshall Islands area for a 100-day period in 1956. The dependence of the cloud mass flux distribution on radiative cooling, large-scale vertical motion, and evaporation from the sea is examined. It is shown that typical radiative cooling rates in the tropics tend to produce a bimodal distribution of mass spectrum exhibiting deep and shallow clouds. The bimodal distribution is further enhanced when the large-scale vertical motion is upward, and a nearly unimodal distribution of shallow clouds prevails when the relative cooling is compensated by the heating due to the large-scale subsidence. Both deep and shallow clouds are modulated by large-scale disturbances. The primary role of surface evaporation is to maintain the moisture flux at the cloud base.

Yanai, M.↗