Polar nano-regions enable large spin Hall conductivity in metallic PtCoO₂

Spin-source materials for spintronic devices are required to convert charge currents into spin currents efficiently and maintain minimal electrical losses. However, conventional strategies to enhance charge-spin conversion often come at the cost of increasing ohmic dissipation. Here we demonstrate that introducing polar lattice distortions into a highly conductive metal can overcome this trade-off. We report the discovery of polar displacements in PtCoO₂ and show that these displacements enhance charge-spin conversion by two orders of magnitude compared with its non-polar phase. The coexistence of polarity and metallicity yields a room-temperature spin Hall conductivity of 1.6 × 10⁷ℏ/2e (Ω m)^-1. Electron ptychography reveals that the inversion-symmetry breaking originates from local polar nano-regions. Polar PtCoO₂ drives efficient spin-orbit torque switching with substantially reduced switching voltage and power compared with Pt-based control devices, and is compatible with silicon substrates, establishing a strategy for designing highly efficient spin-source materials.