Probing slow glass dynamics down to 10−5 Hz

Relaxation processes play a crucial role in glassy materials. However, current dielectric or mechanical spectroscopy typically reaches a lower limit of around 10−1 or 10−2 Hz, which restricts the exploration of long-time dynamics and stability. Here, we propose a mechanical protocol that enables the probing of relaxation processes down to 10−5 Hz, extending the lower limit by ∼3–4 orders of magnitude. The effectiveness of this method is demonstrated in investigating metallic glasses, where the primary and secondary relaxations are detected over an extended timescale. An additional relaxation process has been captured below 10−4 Hz, indicating the emergence of more complex relaxation phenomena over longer timescales. This progress in probing long-term dynamics opens up new possibilities for advancing glassy physics and material properties.