Low-temperature anomalies of a vapor deposited glass

TL;DR

This study examines the low-temperature behavior of vapor-deposited and cooled glass films, revealing a crossover temperature where dynamics and heterogeneity change, with implications for ultra-stable glasses.

Contribution

It identifies a crossover temperature in vapor-deposited glasses where vibrational anomalies emerge, linking stability to low-temperature properties.

Findings

Deep in the solid phase, a crossover temperature $T^*$ is identified.

Localized defects appear around $T^*$, causing vibrational anomalies.

Lower inherent structure energy samples have a decreased $T^*$, indicating suppressed anomalies in ultra-stable glasses.

Abstract

We investigate the low temperature properties of two-dimensional Lennard-Jones glass films, prepared in silico both by liquid cooling and by physical vapor deposition. We identify deep in the solid phase a crossover temperature $T^*$, at which slow dynamics and enhanced heterogeneity emerge. Around $T^*$, localized defects become visible, leading to vibrational anomalies as compared to standard solids. We find that on average, $T^*$ decreases in samples with lower inherent structure energy, suggesting that such anomalies will be suppressed in ultra-stable glass films, prepared both by very slow liquid cooling and vapor deposition.