Magnetic field effect on the dielectric constant of glasses: Evidence of disorder within tunneling barriers

TL;DR

This study investigates how magnetic fields influence the dielectric constant of glasses at very low temperatures, revealing disorder within tunneling barriers as a key factor affecting dielectric properties.

Contribution

It provides the first quantitative interpretation linking magnetic field effects on dielectric constant to disorder within tunneling barriers in glasses.

Findings

Magnetic field dependence of dielectric constant observed at millikelvin temperatures.

Disorder within tunneling barriers explains the magnetic field effects.

Results align with recent theories on interactions in glassy systems.

Abstract

The magnetic field dependence of the low frequency dielectric constant $e_r$(H) of a structural glass a - SiO2 + xCyHz was studied from 400 mK to 50 mK and for H up to 3T. Measurement of both the real and the imaginary parts of $e_r$ is used to eliminate the difficult question of keeping constant the temperature of the sample while increasing H: a non-zero $e_r$(H) dependence is reported in the same range as that one very recently reported on multicomponent glasses. In addition to the recently proposed explanation based on interactions, the reported $e_r$(H) is interpreted quantitatively as a consequence of the disorder lying within the nanometric barriers of the elementary tunneling systems of the glass.