Quantized thermal conductance in metallic heterojunctions

Abstract

It is critical to understand how charge and heat are transferred at the nanoscale in order
to create next-generation electronics and high-efficiency energy-harvesting devices for
future applications. When it comes to probing the quantum limitations of transport,
metallic atomic-size contacts are perfect systems. Several recent studies have shown that
the thermal conductance and electrical conductance of gold atomic contacts may be
quantized at room temperature. However, the quick breaking dynamics of metallic
junctions at room temperature, which might surpass the average reaction time of the
thermal measurement, represents a significant experimental barrier in such studies. An
integrated heater that also serves as a thermometer is used in this break-junction
arrangement, which combines Scanning Tunneling Microscopy with suspended
microelectromechanical systems with a gold-covered membrane. Other metals, including
as Pt, PtIr, and W, were used as tip materials instead of gold to demonstrate heat transfer
measurements across single gold atomic contacts. The relationship between thermal
conductivity and contact size is investigated as a function of the contact size and the
materials employed. In our experiments, we have discovered that by utilising Pt and Pt-
Ir tips, we may increase the mechanical stability and likelihood of creating single Au
atomic connections. In the next section, we demonstrate the quantization of electrical
and thermal conductances, followed by a demonstration of the Wiedemann-Franz law at
the atomic scale. We anticipate that these discoveries will expand the flexibility of
experimental methodologies for examining heat transport in metallic quantum point
contacts, as well as the ability to investigate the thermal characteristics of molecular
junctions.