Abstract
We study the thermal rectification efficiency, i.e., quantification of asymmetric heat flow, of a one-dimensional mass-graded anharmonic oscillator Fermi-Pasta-Ulam lattice both with nearest-neighbor (NN) and next-nearest-neighbor (NNN) interactions. The system presents a maximum rectification efficiency for a very precise value of the parameter that controls the coupling strength of the NNN interactions, which also optimizes the rectification figure when its dependence on mass asymmetry and temperature differences is considered. The origin of the enhanced rectification is the asymmetric local heat flow response as the heat reservoirs are swapped when a finely tuned NNN contribution is taken into account. A simple theoretical analysis gives an estimate of the optimal NNN coupling in excellent agreement with our simulation results.
Highlights
While electronics has been able to control the charge flow for decades, the manipulation of heat current remains elusive more than 80 years after the first experimental observation of asymmetric heat flow in solids [1]
For small γ values, r tends to the value in the case when there are no NNN interactions
In this work we have performed the study of the rectification properties of an anharmonic mass-graded lattice with NNN interactions
Summary
While electronics has been able to control the charge flow for decades, the manipulation of heat current remains elusive more than 80 years after the first experimental observation of asymmetric heat flow in solids [1]. Besides the coupling of a few asymmetric segments [4,5,6] another way to produce the required asymmetry for thermal rectification to occur is to consider a mass gradient along the system length This idea was first employed to experimentally build a rectifying device with a carbon and boron-nitride nanotube inhomogeneously mass-loaded with heavy molecules [9]. In this paper we address the problem of improving the thermal rectification of a mass-graded anharmonic lattice [10,11] by the addition of next-nearest-neighbor (NNN) interactions This system allows to study in a systematic way the effect on thermal rectification of forces with significant magnitude beyond the NN range.
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