Study on momentum density in narrow-gap mixed III-V alloys by positron annihilation under pressure

The pressure dependence of the electron-positron momentum density in InAs_xSb_1-x was studied. The computational technique used here is based on the independent particle model coupled with the use of the electron pseudo-wave functions. The variation of the momentum density versus pressure is weak and shows that InAs_xSb_1-x exhibits a more metallic character. The observation that the calculated total positron annihilation rate increases with pressure has been explained in terms of increased positron penetration into the ion cores. The obtained results have an essential role in the determination of the electronic band structure of narrow gap mixed III-V alloys under pressure.