# Thermal transport in long-range interacting Fermi-Pasta-Ulam chains

## TL;DR

This study investigates thermal transport in long-range interacting Fermi-Pasta-Ulam chains, revealing a nonballistic power-law divergence of thermal conductivity with a larger scaling exponent at a specific interaction range, influenced by unique diffusion and breather dynamics.

## Contribution

The paper introduces a novel approach using reverse thermal baths to study long-range interactions, uncovering enhanced thermal conductivity scaling and underlying mechanisms.

## Key findings

- Thermal conductivity diverges as a power-law with system size, with an exponent around 0.7.
- The scaling exponent can be larger than in short-range systems at a specific LR exponent.
- Unique heat diffusion and breather dynamics influence the thermal transport behavior.

## Abstract

Studies of thermal transport in long-range (LR)interacting systems are currently particularly challenging. The main difficulties lie in the choice of boundary conditions and the definition of heat current when driving systems in an out-of-equilibrium state by the usual thermal reservoirs. Here, by employing a reverse type of thermal baths that can overcome such difficulties, we reveal the intrinsic features of thermal transport underlying a LR interacting Fermi-Pasta-Ulam chain. We find that under an appropriate range value of LR exponent $\sigma =2$, while a \emph{nonballistic} power-law length ($L$) divergence of thermal conductivity $\kappa$, i.e., $\kappa \sim L^{\alpha}$ still persists, its scaling exponent $\alpha \simeq 0.7$ can be much larger than the usual predictions in short-range interacting systems. The underlying mechanism is related to the system's new heat diffusion process, weaker nonintegrability and peculiar dynamics of traveling discrete breathers. Our results shed light on searching for low-dimensional materials supporting higher thermal conductivity by involving appropriate LR interactions.