Ferromagnetism stabilized by lattice distortion at the surface of the p-wave superconductor Sr(2)RuO(4)

Ferromagnetic (FM) spin fluctuations are believed to mediate the spin-triplet pairing for the p-wave superconductivity in Sr(2)RuO(4). Our experiments show that, at the surface, a bulk soft-phonon mode freezes into a static lattice distortion associated with an in-plane rotation of the RuO(6) octahedron. First-principle calculations confirm this structure and predict a FM ground state at the surface. This coupling between structure and magnetism in the environment of broken symmetry at the surface allows a reconsideration of the coupling mechanism in the bulk.

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