Signature of Martensite transformation on conductivity noise in thin films of NiTi shape memory alloys

TL;DR

This study investigates how martensitic transformation affects electrical resistance noise in NiTi thin films, revealing large, non-monotonic fluctuations linked to structural defect dynamics, and proposes a new noise-based characterization method.

Contribution

It introduces a novel noise measurement approach to detect martensitic transformation in NiTi thin films, highlighting defect dynamics as a key factor.

Findings

Noise magnitude is significantly higher than in simple metals.

Resistance noise exhibits non-monotonic behavior around the transformation.

Proposes a new noise-based method for characterizing martensite transformation.

Abstract

Slow time-dependent fluctuations, or noise, in the electrical resistance of dc magnetron sputtered thin films of Nickel Titanium shape memory alloys have been measured. Even in equilibrium, the noise was several orders of magnitude larger than that of simple diffusive metallic films, and was found to be non-monotonic around the martensitic transformation regime. The results are discussed in terms of dynamics of structural defects, which also lay foundation to a new noise-based characterization scheme of martensite transformation.