for the first time, ibm scientists, along with students from eth zurich, successfully measured the thermal conductance of metallic quantum point contacts, composed of gold, to the single-atom level at room temperature, according to a post on the company’s blog.

ibm researchers used a novel technique to measure a single quantum of heat.
(ibm)

as the blog noted, there is increased interest across the electronics industry in measuring and monitoring heat dissipation at the nanoscale level in order to optimize device reliability as component density and miniaturization increases.

in order to try and measure nanoscale heat dissipation, ibm researchers developed a novel technique last year. they created a scanning probe thermometry technique that measures two signals simultaneously. it measures a small heat flux and resistance to heat flow in the nanoscale object. according to the ibm blog, “combining these two signals, the temperature of nanoscopic objects can then be quantified for an accurate result.”

that technique allowed the scientists to measure the temperature of objects at or below 10 nanometers, which allowed heat mapping on a chip. this year, the scientists wanted to go even smaller.

the scientists used a microelectromechanical system (mems) with an integrated thermal sensor that works within a vacuum-based scanning tunneling microscope (stm) and a noise free lab that is shielded from any type of disturbance or outside signal, including the earth’s magnetic field.

as the scientists wrote, “the system essentially combines simultaneous measurements of heat and charge transport to extract the thermal and electrical conductance of metallic contacts. similar to other stm break-junction set-ups, an stm tip is used to form and break few-atom contacts on a substrate covered by a metallic layer. here, however, the bottom electrode is integrated on a suspended mems to insulate it thermally from the chip substrate.”

an article by ieee spectrum explained, “these latest measurements provide further confirmation of the wiedemann–franz law, which predicts that the smallest amount of heat that can be carried across a metallic junction—a single quantum of heat—is directly proportional to the quantum of electrical conductance through the same junction.

“by experimentally confirming this law, it can now be used with confidence to predict and to explore nanoscale thermal and electrical phenomena affecting materials down to the size of few atoms or a single molecule.”

the work was recently published in nature nanotechnology. the abstract o the report stated:

“heat transport and dissipation at the nanoscale severely limit the scaling of high-performance electronic devices and circuits. metallic atomic junctions serve as model systems to probe electrical and thermal transport down to the atomic level as well as quantum effects that occur in one-dimensional (1d) systems.

“whereas charge transport in atomic junctions has been studied intensively in the past two decades, heat transport remains poorly characterized because it requires the combination of a high sensitivity to small heat fluxes and the formation of stable atomic contacts. here we report heat-transfer measurements through atomic junctions and analyse the thermal conductance of single-atom gold contacts at room temperature.

“simultaneous measurements of charge and heat transport reveal the proportionality of electrical and thermal conductance, quantized with the respective conductance quanta. this constitutes a verification of the wiedemann–franz law at the atomic scale.”

learn more about the ibm invention of a thermometer that can measure the nanoscale in the video below: