Electric and Magnetic Evolution in Sputter-Deposited Fe_<i>x</i>Si_1−<i>x</i> Alloy Films

Abstract

Fe x Si 1−x alloy lms have been prepared by an rf sputter-deposition method. X-ray diffraction patterns indicate that an amorphous phase is formed for x < 0.8. Temperature dependence of electrical resistivity indicates the following electric evolution. Carrier-excitation from the impurity to the conduction (or valence) bands is dominant for x < 0.2 (the semiconductor regime), the band conduction is affected by strong impurity-and random-scatterings for x > 0.4 (the metallic regime), and the carrier-excitation between the impurity band and the mobility edge is retained due to the electron-localization effect in the amorphous structure for 0.2 < x < 0.4 (the transition region). The thermomagnetic-and magnetization-curves indicate the following magnetic evolution. The ferromagnetic phase appears at x ≅ 0.3 and the Curie temperature rapidly increases with increasing x. The magnetic (spin-or cluster-) glass region is very narrow (x = 0.3 ∼ 0.55) at low temperature. These magnetic behaviors are ascribed to the instability of Fe magnetic moments and the depression of RKKY interactions in the low x range.

Universal Scaling near Band-Tuned Metal-Insulator Phase Transitions

“…4. The dimensionless temperature coefficient of the resistance versus the dimensionless resistance, for a variety of materials [5,9,23,[27][28][29][30][31][32] (for details, see Ref. [19]), compared to our theoretical result of Eq.…”