Electric current as a stabilizing thermodynamic field in metallic crystals

Electric current, often associated with electromigration and degradation, can instead act as a stabilizing thermodynamic field that freezes lattice rearrangement through a purely electronic mechanism. In situ synchrotron X-ray diffraction and nanodiffraction reveal that this current density (1.5 × 10 ³ A cm⁻ ² ) stabilizes hexagonal η-Cu ₆ Sn ₅ via orientation-dependent elastic distortion, suppressing the partial η → η' transformation otherwise observed at the homologous temperature (~130 °C). Electron-wind momentum produces anisotropic strain (+1.3 % along ⟨0001⟩, −0.8 % in basal planes) and plane-selective dislocation rearrangement, followed by reversible lattice recovery once the current ceases after 5 h. The associated stress (30–40 MPa) and elastic-energy density (9–12 MJ m⁻ ³ ) remain well below the ≈150 MJ m⁻ ³ reconstructive barrier, defining an electron-wind-driven elastic-freezing regime. Electric current thereby complements temperature and mechanical stress as a controllable thermodynamic variable that governs phase stability in conductive lattices and provides direct structural evidence that current density enters the Gibbs free energy as a thermodynamic state variable, defining an elastic-freezing regime in T––J space.