Magnetotransport properties of nonstoichiometric Si-Mn alloys with an excess of manganese relative to silicides Mn4Si7 and MnSi

Comparative examination of magnetotransport properties of nonstoichiometric Si1-x Mn (x) alloys with roughly the same (delta N.../x ae 7%) excess of Mn relative to silicides Mn4Si7 and MnSi has been performed. Films of Si1-x Mn (x) (N... ae 0.39 and 0.535) with a thickness of 60-70 nm have been fabricated by means of pulsed laser deposition on Al2O3 (0001) substrates at a temperature of 340A degrees D<inverted exclamation>. It has been found that the excess of Mn produces the strongest effect on the Curie temperature in the case of MnSi (D cent (D<inverted exclamation>) increases from 30 K to 300 K and higher), while no such effect is observed in Mn4Si7. This may be attributed to strong nonmagnetic disorder in Si1-x Mn (x) with x ae 0.39 and the associated unusual behavior of negative magnetoresistance (NMR): The NMR varies linearly with magnetic field at D' ae<currency> 1.3 T and exhibits almost no temperature dependence at T = 40-85 K.