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要旨:
This work reports experiments and first-principles calculations on the
substitutional semiconducting C1(b) compound CoTi1-xMxSb. Diluted
magnetic semiconductors have been prepared by substituting titanium in
the semiconducting compound CoTiSb by other 3d transition elements M.
Self-consistent calculations of the electronic structure predict some of
the materials to be half-metallic ferromagnets. The structural,
electronic, electric, and magnetic properties of the pure and
substituted materials have been investigated. It is found from the
experiments that substitution of up to 10% Ti by Fe, Mn, Cr, and V does
not affect the crystalline structure and the lattice mismatch is less
than 0.5% in the substituted compounds. The electric properties can be
tuned from semiconducting to metallic by using different dopants. The
M=Cr-doped compound exhibits a metal to semiconductor transition.
Photoemission spectroscopy and conductivity measurements agree well with
the calculated electronic structure. The measured Curie temperature of
the Fe-substituted alloy is far above room temperature (>700 K). This
fact and the very low lattice mismatch between the substituted and the
pure compound make this material a serious candidate for future
electronic applications, in particular for magnetoelectronics and
spintronics.
