Temperature dependence of electrical resistivity in (Fe1-xTix)3Al alloys
Abstract
We report on the temperature dependence of electrical resistivity in (Fe1-xTix)3Al alloys with Ti compositions x = 0-0.33. Samples in the composition range 0≤x≤0.15 are found to exhibit ferromagnetism with the Curie temperature TC decreasing from 770 K for x = 0 to 145 K for x = 0.15. The electrical resistivity below about 400 K for these Ti-poor samples increases rapidly with increasing x, but a negative temperature derivative of resistivity (dρ/dT) dominates above TC up to 1000 K and above. In contrast, samples in the range 0.20≤x≤0.33 are in a paramagnetic state, at least down to 2 K, and exhibit a rapid decrease in the low-temperature resistivity with increasing Ti composition x. In particular, the Heusler-type Fe2TiAl (x = 0.33) shows a large positive dρ/dT with the residual resistivity of only about 20 µΩ cm, in sharp contrast to a closely related system Fe2VAl reminiscent of a semiconductor-like behaviour with the resistivity reaching 3000 µΩ cm at 2 K. This can be explained by the fact that Fe2TiAl possesses a much higher density of states at the Fermi level than Fe2VAl, as deduced from the low-temperature specific-heat measurements supplemented by the band calculations in literature. The reason for the possession of a large positive dρ/dT in Fe2TiAl is discussed in relation to the Bloch-Grüneisen law.
- Publication:
-
Journal of Physics Condensed Matter
- Pub Date:
- October 2000
- DOI:
- 10.1088/0953-8984/12/43/305
- Bibcode:
- 2000JPCM...12.9153K