Long range diffusion noise in platinum micro-wires with metallic adhesion layers

Voltage fluctuations of Platinum wires hosted by silicon nitride beams were investigated. We considered four variants of the wires: three with an adhesion layer and one with no adhesion layer. We found that the presence of an adhesion layer changes the nature of the power spectrum which is $1/f$ for wires with no adhesion layers and $1/f^{3/2}$ for wires with an adhesion layer. We attribute the value of the exponent $\alpha=3/2$ to the long range diffusion of hydrogen originating from adhesion layers that undergo a migration through the Pt wires.