Electronic structure of paramagnetic In<Subscript>1-x</Subscript>Mn<Subscript>x</Subscript> As nanowires

The electronic structure, spin splitting energies, and g factors of paramagnetic In<Subscript>1-x</Subscript>Mn<Subscript>x</Subscript>As nanowires under magnetic and electric fields are investigated theoretically including the sp-d exchange interaction between the carriers and the magnetic ion. We find that the effective g factor changes dramatically with the magnetic field. The spin splitting due to the sp-d exchange interaction counteracts the Zeeman spin splitting. The effective g factor can be tuned to zero by the external magnetic field. There is also spin splitting under an electric field due to the Rashba spin-orbit coupling which is a relativistic effect. The spin-degenerated bands split at nonzero k<Subscript>z</Subscript> (k<Subscript>z</Subscript> is the wave vector in the wire direction), and the spin-splitting bands cross at k<Subscript>z</Subscript>=0, whose k<Subscript>z</Subscript>-positive part and negative part are symmetrical. A proper magnetic field makes the k<Subscript>z</Subscript>-positive part and negative part of the bands asymmetrical, and the bands cross at nonzero k<Subscript>z</Subscript>. In the absence of magnetic field, the electron Rashba coefficient increases almost linearly with the electric field, while the hole Rashba coefficient increases at first and then decreases as the electric field increases. The hole Rashba coefficient can be tuned to zero by the electric field. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007