top – upper critical magnetic field graph. bottom – specimen in pressure cell

1. Superconductivity in CaFe2As2 under pressure Milton Torikachvili, San Diego State University Foundation, DMR 0805335 The CaFe2As2 compound is quite remarkable. A structural transformation near 170 K prevents the occurrence of superconductivity at lower temperatures. However, uniaxial or slightly non-hydrostatic pressures of ~3 katm suppress this transformation, and superconductivity appears near 12 K. A further increase of pressure brings about another structural modification, and superconductivity disappears again for pressures above ~ 10 katm. Measurements of the Hall effect, critical magnetic field, and magnetoresistance under pressure, are consistent with the formation of a robust superconducting state for pressures between 3 and 10 katm. The magnetoresistance in the high-pressure phase at 0.3 K increases linearly with magnetic field up to 31 T, which is quite unusual. Similar behavior has been observed before only in some anisotropic semimetals. Physical Review B80, 14521 (2009). top – upper critical magnetic field graph. bottom – specimen in pressure cell sample holder.

2. Superconductivity in CaFe2As2 under pressure Milton Torikachvili, San Diego State University Foundation, DMR 0805335 Education Funding for this award facilitated the engagement of several graduate and undergraduate students in cutting edge research and technologies. Outreach The PI and students developed a set of demonstrations and exhibits. We take these demos to high schools, campus open-houses, and we use them when hosting the visit of local students to the campus. Local students visiting the campus for science sampler day. Students from the Mission Hills school district visiting the laboratories at San Diego State.