Paramagnetic tunneling systems and their contribution to the polarization echo in glasses (extended)

TL;DR

This paper explains magnetic effects on polarization echo in silicate glasses at low temperatures through a paramagnetic tunneling system mechanism, fitting experimental data for Fe, Cr, and Nd impurities.

Contribution

It introduces a novel tunnel mechanism involving paramagnetic impurities to quantitatively explain magnetic effects on polarization echo in glasses.

Findings

Magnetic field effects can be modeled with paramagnetic tunneling systems.

Fits to experimental data for Fe, Cr, and Nd-doped glasses are successful.

The mechanism accounts for temperature and magnetic field dependence.

Abstract

Startling magnetic effects on the spontaneous polarization echo in some silicate glasses at low and ultra-low temperatures have been reported in the last decade or so. Though some progress in search of an explanation has been made by considering the nuclear quadrupole dephasing of tunneling particles, here we show that the effect of a magnetic field can be understood quantitatively by means of a special tunnel mechanism associated with paramagnetic impurities. For the Fe-, Cr- and Nd-contaminated glasses we provide reasonable fits to the published data as a function of applied magnetic field and temperature.