Multi-Welled Tunneling Model for the Magnetic-Field Effect in Ultracold Glasses

TL;DR

This paper introduces a multi-welled tunneling model to explain the magnetic field effects on thermal and dielectric properties in ultracold glasses, extending the standard two-level systems framework.

Contribution

It proposes a new model incorporating multi-welled tunneling systems to account for magnetic field effects in low-temperature glass responses.

Findings

The model captures the temperature and magnetic field dependence of specific heat and dielectric constant.

It suggests the existence of anomalous multi-welled tunneling systems in glasses.

Indicates potential for larger electric magnetocapacitive effects in certain glasses.

Abstract

Puzzling observations of both thermal and dielectric responses in multi-silicate glasses at low temperatures $T$ to static magnetic fields $B$ have been reported in the last decade and call for an extension of the standard two-level systems tunneling model. An explanation is proposed, capable of capturing at the same time the $T$- and $B$-dependence of the specific heat $C_p$ and of the dielectric constant $\epsilon$ in these glasses. This theory points to the existence of anomalous multi-welled tunneling systems in the glasses -- alongside the standard two-level systems -- and indications are given for glasses which should achieve larger electric magnetocapacitive enhancements.