Fig. 2.

Violation of the Wiedemann–Franz law. a False-colored SEM image of a microdevice for measuring thermal transport that consist of two suspended platforms bridged by a 2.5-μm-wide WP₂ ribbon. The scale bar denotes 100 μm. b Thermal conductivity κ (left axis) and electrical resistivity ρ (right axis) of the micro-ribbon as a function of temperature. The error bars denote the error of the measurement as described in the Supporting Information. c Lorenz number L = κTρ, calculated from the data in b in units of the Sommerfeld value L₀. The error bars denote the error, coming from the thermal conductivity measurements. The inset shows a zoom of the low-temperature region