Thermal energy and charge currents in multi-terminal nanorings

Tobias Kramer,Andreas D Wieck,Dirk Reuter,Saskia F Fischer,Olivio Chiatti,Sven S Buchholz,Christoph Kreisbeck,Christian Riha

doi:10.1063/1.4953812

Tobias Kramer, Andreas D Wieck + Show 6 more

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https://doi.org/10.1063/1.4953812

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Abstract

We study in experiment and theory thermal energy and charge transfer close to the quantum limit in a ballistic nanodevice, consisting of multiply connected one-dimensional electron waveguides. The fabricated device is based on an AlGaAs/GaAs heterostructure and is covered by a global top-gate to steer the thermal energy and charge transfer in the presence of a temperature gradient, which is established by a heating current. The estimate of the heat transfer by means of thermal noise measurements shows the device acting as a switch for charge and thermal energy transfer. The wave-packet simulations are based on the multi-terminal Landauer-Büttiker approach and confirm the experimental finding of a mode-dependent redistribution of the thermal energy current, if a scatterer breaks the device symmetry.

Highlights

Quantized conductance steps of an electric current through an electron waveguide with a constriction are a hallmark of ballistic transport[1,2,3] and have been successfully modelled within the Landauer-Büttiker approach.[4,5,6] In the ballistic transport theory, the scattering and transmission coefficients of the geometry regulate the flux through the system of non-interacting electrons.Injected electrons inherit the properties of the reservoirs from which they come from and no dephasing or dissipation occurs within the ballistic system
We study in experiment and theory thermal energy and charge transfer close to the quantum limit in a ballistic nanodevice, consisting of multiply connected one-dimensional electron waveguides
The fabricated device is based on an AlGaAs/GaAs heterostructure and is covered by a global top-gate to steer the thermal energy and charge transfer in the presence of a temperature gradient, which is established by a heating current

Summary

INTRODUCTION

Quantized conductance steps of an electric current through an electron waveguide with a constriction are a hallmark of ballistic transport[1,2,3] and have been successfully modelled within the Landauer-Büttiker approach.[4,5,6] In the ballistic transport theory, the scattering and transmission coefficients of the geometry regulate the flux through the system of non-interacting electrons. The presence of junctions and crossings in a multi-terminal device requires to calculate the electric and thermal transport for the specific sample geometry across a range of Fermi energies. This task is facilitated by switching to a time-dependent intermediate representation of the quantum-mechanical transport, using wave packets which are decomposed into plane wave components pointing to the different terminals.[18,19] The theoretical model elucidates the origin of the observed mode-dependent branching ratio of the device[10] by connecting it to specific device imperfections

CONDUCTION IN A MULTI-TERMINAL DEVICE

BALLISTIC TRANSPORT PROPERTIES

THERMAL ENERGY CURRENT IN A MULTI-TERMINAL DEVICE

CONCLUSIONS