2009/09/18 by Fei Zhan, Nianbei Li, Sigmund Kohler +1
Engineering · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Molecular Junctions and Nanostructures #Quantum and electron transport phenomena #cond-mat.mes-hall #cond-mat.stat-mech
paper · pdf · doi:10.1103/physreve.80.061115
published as published in Phys. Rev. E 80, 061115 (2009) · 9 pages, 8 figures
arxiv created 2009/09/18 · openalex publication_date 2009/12/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We explore heat transfer in molecular junctions between two leads in the absence of a finite net thermal bias. The application of an unbiased time-periodic temperature modulation of the leads entails a dynamical breaking of reflection symmetry, such that a directed heat current may emerge (ratchet effect). In particular, we consider two cases of adiabatically slow driving, namely, (i) periodic temperature modulation of only one lead and (ii) temperature modulation of both leads with an ac driving that contains a second harmonic, thus, generating harmonic mixing. Both scenarios yield sizable directed heat currents, which should be detectable with present techniques. Adding a static thermal bias allows one to compute the heat current-thermal load characteristics, which includes the ratchet effect of negative thermal bias with positive-valued heat flow against the thermal bias, up to the thermal stop load. The ratchet heat flow in turn generates also an electric current. An applied electric stop voltage, yielding effective zero electric current flow, then mimics a solely heat-ratchet-induced thermopower ("ratchet Seebeck effect"), although no net thermal bias is acting. Moreover, we find that the relative phase between the two harmonics in scenario (ii) enables steering the net heat current into a direction of choice.