Two-Level Systems and Boson Peak Remain Stable in 110-Million-Year-Old Amber Glass

TL;DR

This study demonstrates that key low-temperature features of glasses, such as tunneling two-level systems and the boson peak, remain unchanged even after 110 million years of natural aging in amber, challenging previous assumptions.

Contribution

It provides evidence that the low-temperature vibrational properties of glasses are remarkably stable over geological timescales, even in highly stabilized natural glass samples.

Findings

Two-level systems are unchanged after 110 million years.

The boson peak remains stable in aged amber.

Aging does not affect low-temperature vibrational features.

Abstract

The two most prominent and ubiquitous features of glasses at low temperatures, namely the presence of tunneling two-level systems and the so-called boson peak in the reduced vibrational density of states, are shown to persist essentially unchanged in highly stabilized glasses, contrary to what was usually envisaged. Specifically, we have measured the specific heat of 110 million-year-old amber samples from El Soplao (Spain), both at very low temperatures and around the glass transition Tg. In particular, the amount of two-level systems, assessed at the lowest temperatures, was surprisingly found to be exactly the same for the pristine hyperaged amber as for the, subsequently, partially and fully rejuvenated samples.