A thermometer that turns a heat flow into an electrical signal: that's the anomalous Nernst effect: in a magnetic material, heat generates a transverse voltage. Until now, engineers could only tweak this signal slightly by changing the proportions of two metals. The new work adds a third component, and the picture gets dramatically more complex.
The authors took amorphous films of three elements (gadolinium, cobalt, and platinum) and mapped their properties. It turned out that in the ternary 'space' of compositions, you can independently control both the magnitude of the thermoelectric response and how well the material conducts heat. The balance between these two parameters determined the sensor's sensitivity — about 0.24 micrometers per ampere. Previously, such adjustments required switching the entire pair of metals; now, you just smoothly shift the platinum concentration.
The work is like tuning a musical instrument: instead of two strings, you're handed a third, and the chord becomes richer. So here: moving from binary to ternary alloys opened up new degrees of freedom. In the future, this will allow creating compact heat-flux sensors that can be precisely adapted to a specific task — from cooling microchips to harvesting waste heat.
The anomalous Nernst effect occurs only in magnetic materials and disappears if you remove the magnetization — unlike the ordinary Nernst effect, which is present in almost any conductor.