Asymmetry of a complex gap near the Fermi level, determined from measurements of the thermopower in La_{1 <i>x</i>}Ca_<i>x</i>Mn_{1 <i>y</i>}Fe_<i>y</i>O₃

Abstract

The experimental data are analysed quantitatively with a percolation model using results of our recent investigations of the Shklovskii–Efros-like variable-range hopping conductivity in the same set of La₁₋xCaxMn₁₋yFeyO₃ samples with evidence for a soft Coulomb gap and a rigid gap in the density of states near the Fermi level