Weak-localization and Maki-Thompson superconducting fluctuation effects in crystalline disordered Ti-Al-(Sn,Co) alloys at T>Tc

Abstract

We have measured the magnetoresistivities of crystalline disordered Ti1−xAlx−y(Sn,Co)y x=0.072 and y≤0.03 alloys between 1.7 and 15 K in magnetic fields up to 3 T. With a total doping level of 7.2 at.% for Ti, our samples are disordered enough to manifest quantum corrections due to weak-localization and electron-electron interaction effects. As the magnetic field B is increased, magnetoresistivities Δρ(B)ρ(0)=[ρ(B)−ρ(0)]ρ(0) of the order of 10−4-10−3 are observed. Both the functional forms and magnitudes of the observed Δρ(B) are interpreted in terms of weak-localization and Maki-Thompson superconducting fluctuation effects. Our sample compositions (i.e., additions of y=0.000, 0.030 of Sn, and 0.0005 of Co, respectively, for Al) have been chosen so as to tailor the various aspects of both effects. We find that spin-orbit scattering is greatly increased in the alloy containing 3.0 at.% of Sn. As a result, Δρ(B) increases monotonically with increasing B in all our measuring magnetic fields and at all measuring temperatures. In the alloy containing 0.05 at.% of Co, superconducting fluctuation effects are greatly enhanced at our measuring temperatures, and a diverging inelastic scattering rate is observed in our lowest temperature range of 1.7-1.9 K. From comparison of our experimental results with theory, the inelastic scattering times have been inferred and ascribed to electron-phonon interaction in the presence of strong impurity scattering. Our results suggest that, in the crystalline disordered metals like our Ti-Al-(Sn,Co) alloys, the electron-phonon scattering rate varies with the square of the temperature, τph−1∼T2, in the temperature range 3-15 K. Particularly, the absolute magnitudes of the measured τph are consistent within ∼40% with the theoretical prediction.

Source-reported materials — not catalogue approval

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