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

Specific power generation capacity Γ_P 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 Γ_P of ∼5000 µW cm^-2 K^-2 in μ-TEGs based on the anomalous Nernst effect (ANE) in medium-entropy (FeCoNi)_{100- x}Pt_x films. Leveraging the high-entropy cocktail strategy, we have simultaneously achieved a large anomalous Nernst thermopower S_xy (>1.4 µV K^-1) and low resistivity ρ_xx (<85 µΩ cm), and suppressed the classical and quantum size effects on both S_xy and ρ_xx at the optimal composition of x ≈ 50 and film thickness of a few nanometers, enabling the record-high Γ_P. 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.