Dielectric constant of glasses: first observation of a two-dimensional behavior

Abstract

The 1kHz real part $χ&#39;$ of the dielectric constant of a structural glass was measured at low temperature $T$ down to 14 mK. Reducing the sample thickness $h$ to 10 nm suppresses the usual minimum of $χ&#39;$ for measuring fields $E<.5 $ MV/m. This contradicts the Two Level System (TLS) model but is well accounted for by including TLS-TLS interactions where excitations delocalize between TLS&#39;s through a $E$-induced mechanism recently designed: for small $h$&#39;s this interaction is reduced, which explains the two-dimensional behavior of $χ&#39;(T)$. Hence, interactions play a key role in standard thick samples.