233,733 research outputs found
A New Spin Gapless Semiconductors Family: Quaternary Heusler Compounds
Using first-principles calculations, we investigate the band structures of a
series of quaternary LiMgPdSn-type Heusler compounds. Our calculation results
show that five compounds CoFeMnSi, CoFeCrAl, CoMnCrSi, CoFeVSi and FeMnCrSb
possess unique electronic structures characterized by a half-metallic gap in
one spin direction while a zero-width gap in the other spin direction showing
spin gapless semiconducting behavior. We further analysis the electronic and
magnetic properties of all quaternary Heusler alloys involved, and reveal a
semi-empirical general rule (total valence electrons number being 26 or 28) for
indentifying spin gapless semiconductors in Heusler compounds. The influences
of lattice distortion and main-group element change have also been discussed.Comment: 20 pages, 5 figures, 1 supplementary file, submitted for publicatio
Evasion in the plane
Dynamic systems were considered subject to control by two agents, one of whom desires that no trajectory of the system emanating from outside a given set, intersects that set no matter what the admissible actions of the other agent. Constructive conditions sufficient to yield a feedback control for the agent seeking avoidance were employed to deduce an evader control for the planar pursuit-evasion problem with bounded normal accelerations
Intrinsic electron-doping in nominal "non-doped" superconducting (La,Y)CuO thin films grown by dc magnetron sputtering
The superconducting nominal "non-doped" (LYCO) thin
films are successfully prepared by dc magnetron-sputtering and in situ
post-annealing in vacuum. The best more than 13K is achieved in the
optimal LYCO films with highly pure c-axis oriented T'-type structure. In the
normal state, the quasi-quadratic temperature dependence of resistivity, the
negative Hall coefficient and effect of oxygen content in the films are quite
similar to the typical Ce-doped T'-214 cuprates, suggesting that T'-LYCO shows
the electron-doping nature like known n-type cuprates, and is not a band
superconductor as proposed previously. The charge carriers are considered to be
induced by oxygen deficiency.Comment: 5 pages, 7 figure
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