Heat transport and self-organized criticality in liquid 4He close to T_lambda

TL;DR

This paper uses renormalization-group calculations to analyze heat transport and self-organized criticality in superfluid helium-4 near the lambda transition, considering effects of heat current and gravity.

Contribution

It introduces a theoretical model for thermal conductivity in superfluid helium-4 accounting for gravity and heat flow, and explores self-organized critical states.

Findings

Finite thermal conductivity below T_lambda with dissipation.

Self-organized critical state where gravity and heat current effects cancel.

Comparison with recent experimental data.

Abstract

We present a renormalization-group calculation based on model F for the thermal conductivity lambda_T(T,Q) in the presence of a homogeneous heat current Q and gravity. For temperatures below T_lambda we obtain a large but finite thermal conductivity corresponding to superfluid 4He with dissipation. Furthermore, we consider the self-organized critical state where the effects of gravity and heat current cancel each other so that the distance from criticality delta T = T(z) - T_lambda(z) is constant in space and a function of Q. We compare our theoretical results with recent experiments.