By realizing in thin films a tensile stress state, superconductivity of 13 K was introduced into FeTe, a nonsuperconducting parent compound of the iron pnictides and chalcogenides, with a transition temperature higher than that of its superconducting isostructural counterpart FeSe. For these tensile stressed films, superconductivity is accompanied by a softening of the first-order magnetic and structural phase transition, and also, the in-plane extension and out-of-plane contraction are universal in all FeTe films independent of the sign of the lattice mismatch, either positive or negative. Moreover, the correlations were found to exist between the transition temperatures and the tetrahedra bond angles in these thin films.

FeSe(x) (x = 0.80,0.84,0.88,0.92) thin films were prepared on SrTiO(3)(001)(STO), (La,Sr)(Al,Ta)O(3)(001) (LSAT), and LaAlO(3)(001) (LAO) substrates by a pulsed laser deposition method. All of the thin films show single-phase and c-axis oriented epitaxial growth, and are superconducting. Among them, the FeSe(0.88) thin films show a T(c,onset) of 11.8 K and a T(c,0) of 3.4 K. The upper critical magnetic field is estimated to be 14.0 T.

We demonstrate a large electrical spin injection into GaAs at zero magnetic field thanks to an ultrathin perpendicularly magnetized CoFeB contact of a few atomic planes (1.2 nm). The spin-polarization of electrons injected into GaAs was examined by the circular polarization of electroluminescence from a Spin Light Emitting Diode with embedded InGaAs/GaAs quantum wells. The electroluminescence polarization as a function of the magnetic field closely traces the out-of-plane magnetization of the CoFeB/MgO injector. A circular polarization degree of the emitted light as large as 20% at 25 K is achieved at zero magnetic field.Moreover the electroluminescence circular polarization is still about 8% at room temperature.