Transport anomaly in the low energy regime of spin chains

TL;DR

This paper investigates the low-temperature thermal conductivity in spin chains, showing that Umklapp scattering is irrelevant and explaining the high conductivities observed experimentally, with a focus on the Drude weight's temperature dependence.

Contribution

It provides a theoretical analysis demonstrating the irrelevance of Umklapp terms in low-temperature spin chain transport, aligning with experimental observations.

Findings

Umklapp terms are irrelevant at low temperatures.

High thermal conductivities are consistent with experimental data.

The temperature dependence of the Drude weight is characterized.

Abstract

The anomalous thermal conductivity in spin chains observed in experiments is studied for the low temperature regime. In the effective dynamics with most realistic perturbations, the so-called Umklapp terms is irrelevant to reduce mean free path in the energy transport at even finite temperatures. This is consistent with large conductivities found in recent experiments. The Drude weight which is the prefactor in the divergent conductivity is calculated, and the temperature dependence is discussed.