Journal of magnetism and magnetic materials vol:258 pages:222-224
The comprehensive study of low-temperature magnetization together with DC and AC transport has been carried out in magnetic fields up to 120 kOe in the almost magnetic narrow-gap cubic semiconductor FeSi. The analysis of the experimental data obtained on single crystals of iron monosilicide demonstrates that the Mott-Hubbard scenario of metal-insulator transition with on-site Coulomb interaction Uless than or equal to3D (D is the band half-width) is likely to be the most appropriate description of the low temperature anomalies in the physical properties of this strongly correlated electron system. When the temperature decreases below 100 K, a density of states renormalization together with the formation of short-range (similar to10(17) cm(-3)) spin polarons occurs. Moreover, below T(c)approximate to15 K a transformation of the low-density (similar to10(17)cm(-3)) heavy fermions into ferromagnetic microdomains takes place in the matrix of Fesi. The crossover in magnetic and transport properties of FeSi is discussed in terms of the many-body resonance suppression at higher temperatures T > 100 K. (C) 2002 Elsevier Science B.V. All rights reserved.