title: Symmetry-breaking lattice distortion in Sr₃Ru₂O₇.
abstract: The electronic nematic phase of Sr₃Ru₂O₇ is investigated by high-resolution in-plane thermal expansion measurements in magnetic fields close to 8 T applied at various angles Θ off the c axis. At Θ < 10° we observe a very small (10⁻⁷) lattice distortion which breaks the fourfold in-plane symmetry, resulting in nematic domains with interchanged a and b axis. At Θ ≳ 10° the domains are almost fully aligned and thermal expansion indicates an area-preserving lattice distortion of order 2 × 10⁻⁶ which is likely related to orbital ordering. Since the system is located in the immediate vicinity of a metamagnetic quantum critical end point, the results represent the first observation of a structural relaxation driven by quantum criticality.
authors.affiliation: I. Physikalisches Institut, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Stingl
authors.forename: R S
authors.initials: RS
authors.lastname: Perry
authors.forename: Y
authors.initials: Y
authors.lastname: Maeno
authors.forename: P
authors.initials: P
authors.lastname: Gegenwart