Indications for an “excess wing” in metallic glasses from the mechanical loss modulus in Zr ₆₅ Al 7.5 Cu 27.5

The temperature-dependent complex shear modulus G * of an amorphous, 300 nm thick Zr 65 Al 7.5 Cu 27.5 film is measured using a double-paddle oscillator as a substrate, oscillating in its torsional eigenmode at about 5440 Hz. At high temperatures, the loss modulus is dominated by viscous flow that leads to an α-relaxation peak in the temperature domain. We calculate this peak for our metallic system using the Havriliak-Negami function for the mechanical loss in combination with the Vogel-Fulcher-Tammann equation to describe the temperature-dependent characteristic relaxation time. In the vicinity of the glass transition, we observe a clear experimental deviation from this calculated α-process, which we consider as first indication for the existence of an "excess wing" in metallic systems.