Eur. Phys. J. B 19, 525-529 (2001)
https://doi.org/10.1007/s100510170298

CPA density of states and conductivity in a double-exchange system containing impurities

¹ Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev POB 653, Beer-Sheva 84105, Israel
² Jack and Pearl Resnick Institute of Advanced Technology, Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel

Corresponding author: ^a kogan@quantum.ph.biu.ac.il

Received: 13 June 2000
Revised: 5 January 2001
Published online: 15 February 2001

Abstract

We study density of states and conductivity of the doped double-exchange system, treating interaction of charge carriers both with the localized spins and with the impurities in the coherent potential approximation. It is shown that under appropriate conditions there is a gap between the conduction band and the impurity band in paramagnetic phase, while the density of states is gapless in ferromagnetic phase. This can explain metal-insulator transition frequently observed in manganites and magnetic semiconductors. Activated conductivity in the insulator phase is numerically calculated.