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

Area of Science:

• Condensed matter physics
• Materials science
• Solid-state chemistry

Background:

• Spontaneous polarization echoes in silicate glasses exhibit unusual magnetic field effects at low temperatures.
• Previous explanations involving nuclear quadrupole dephasing of tunneling particles were incomplete.

Purpose of the Study:

• To provide a quantitative explanation for the magnetic field effects on spontaneous polarization echoes in silicate glasses.
• To propose a novel tunnel mechanism involving paramagnetic impurities as the underlying cause.

Main Methods:

• Theoretical modeling of a special tunnel mechanism.
• Quantitative analysis of magnetic field and temperature dependence.
• Fitting published experimental data for specific glass compositions.

Main Results:

• The proposed tunnel mechanism involving paramagnetic impurities successfully explains the observed magnetic effects.
• Reasonable fits were achieved for data from glasses contaminated with Fe(3+), Cr(3+), and Nd(3+).
• The model quantitatively describes the influence of applied magnetic field and temperature.

Conclusions:

• Paramagnetic impurities and their associated tunnel mechanism are key to understanding magnetic field effects on polarization echoes in silicate glasses.
• This provides a more complete explanation than previous models.
• The findings are applicable to specific doped silicate glass systems.