Anomalous negative differential thermal resistance in a momentum-conserving lattice

TL;DR

This paper reports the discovery of anomalous negative differential thermal resistance (NDTR) in a momentum-conserving Fermi-Pasta-Ulam lattice, showing unique temperature-dependent behavior and size effects, expanding understanding of thermal transport phenomena.

Contribution

It presents the first observation of NDTR in a momentum-conserving lattice, revealing its dependence on temperature and system size, and explaining the phenomenon through nonlinear coupling effects.

Findings

NDTR observed in Fermi-Pasta-Ulam lattices, not previously reported in similar models.

NDTR disappears at low temperatures.

The temperature range of NDTR shifts with system size.

Abstract

A two-segment Fermi-Pasta-Ulam lattices has been investigated by using nonequilibrium molecular dynamics. Here we present an anomalous negative differential thermal resistance (NDTR) that have not been reported in Frenkel-Kontorova and \phi_4 lattices up to the present. The NDTR disappears at low temperature region. The region of NDTR shifts from the large to the small temperature difference region as the system size increases. Anomalous dependence of NDTR on the temperature can be explained as the negative effect induced by the nonlinear coupling. The explanation can also cover the phenomenon of NDTR in momentum-nonconserved lattices.