Hopping conductivity and spectrum of localized carriers in β-FeSi:Mn

Abstract

Resistivity measurements of Mn-doped p-type β-FeSi2 single crystals are presented and analyzed with the different hopping conductivity models. Both the Mott and the Shklovskii- Efros regimes of the variable-range hopping (VRH) conductivity are observed as well as the universal scaling behavior of the resistivity. The characteristic and transition temperatures and widths of the impurity band and of the Coulomb gap, Δ, in the density of states (DOS) are obtained, indicating existence of a rigid gap, δ, in the spectrum of DOS, in addition to Δ, which points out to the polaronic nature of the charge carriers in the investigated compound.