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A β‐FeSi₂–SiGe nanocomposite is synthesized via a react/transform spark plasma sintering technique, in which eutectoid phase transformation, Ge alloying, selective doping, and sintering are completed in a single process, resulting in a greatly reduced process time and thermal budget. Hierarchical structuring of the SiGe secondary phase to achieve coexistence of a percolated network with isolated nanoscale inclusions effectively decouples the thermal and electrical transport. Combined with selective doping that reduces conduction band offsets, the percolation strategy produces overall electron mobilities 30 times higher than those of similar materials produced using typical powder‐processing routes. As a result, a maximum thermoelectric figure of meritZTof ≈0.7 at 700 °C is achieved in the β‐FeSi₂–SiGe nanocomposite.

 

Abstract The discovery of two-dimensional (2D) ferromagnets and antiferromagnets with topologically nontrivial electronic band structures makes the study of the Nernst effect in 2D materials of great importance and interest. To measure the Nernst coefficient of 2D materials, the detection of the temperature gradient is crucial. Although the micro-fabricated metal wires provide a simple but accurate way for temperature detection, a linear-response assumption that the temperature gradient is a constant is still necessary and has been widely used to evaluate the temperature gradient. However, with the existence of substrates, this assumption cannot be precise. In this study, we clearly show that the temperature gradient strongly depends on the distance from the heater by both thermoelectric transport and thermoreflectance measurements. Fortunately, both measurements show that the temperature gradient can be well described by a linear function of the distance from the heater. This linearity is further confirmed by comparing the measured Nernst coefficient to the value calculated from the generalized Mott’s formula. Our results demonstrate a precise way to measure the Nernst coefficient of 2D materials and would be helpful for future studies.