Quadrupole Effect on the Heat Conductivity of Cold Glasses

TL;DR

This paper investigates how nuclear quadrupole moments influence the thermal conductivity of glasses at very low temperatures, revealing a crossover in behavior and deviations from standard tunneling theory.

Contribution

It introduces a new theoretical model coupling tunnelling motion with nuclear quadrupoles to explain thermal conductivity variations in glasses at low temperatures.

Findings

Thermal conductivity exceeds standard tunneling predictions below a certain temperature.

A crossover occurs near the nuclear quadrupole energy, altering the temperature dependence.

Standard tunneling results are recovered at higher temperatures.

Abstract

At very low temperatures, the tunnelling theory for amorphous solids predicts a thermal conductivity $\kappa\propto T^p$, with $p = 2$. We have studied the effect of the Nuclear Quadrupole moment on the thermal conductivity of glasses at very low temperatures. We developed a theory that couples the tunnelling motion to the nuclear quadrupoles moment in order to evaluate the thermal conductivity. Our result suggests a cross over between two different regimes at the temperature close to the nuclear quadrupoles energy. Below this temperature we have shown that the thermal conductivity is larger than the standard tunneling result and therefore we have $p < 2$. However, for temperatures higher than the nuclear quadrupoles energy, the result of standard tunnelling model has been found.