Giant Specific Power Generation Capacity of Micro-Thermoelectric Generators Enabled by High-Entropy Cocktail Strategy.

Specific power generation capacity ΓP is a critical performance metric for micro-thermoelectric generators (μ-TEGs), yet the best reported values are constrained to a few hundred µW cm-2 K-2. Here, we report a giant ΓP of ∼5000 µW cm-2 K-2 in μ-TEGs based on the anomalous Nernst effect (ANE) in medium-entropy (FeCoNi)100- xPtx films. Leveraging the high-entropy cocktail strategy, we have simultaneously achieved a large anomalous Nernst thermopower Sxy (>1.4 µV K-1) and low resistivity ρxx (<85 µΩ cm), and suppressed the classical and quantum size effects on both Sxy and ρxx at the optimal composition of x ≈ 50 and film thickness of a few nanometers, enabling the record-high ΓP. The underlying mechanism arises from cocktail-driven modulation of energy-band smearing, density of states, and Berry curvature at the Fermi surface, resulting in an ultrashort carrier mean-free-path of ∼3 nm, an ultrahigh carrier density of ∼1023 cm-3, and a large anomalous Nernst conductivity above 1.7 A m-1 K-1. This claim is further supported by first-principles calculations, which collectively highlight the experimental and theoretical potential of utilizing such materials for high-performance μ-TEG applications.