Strain and vector magnetic field tuning of the anomalous phase in Sr 3 Ru 2 O 7

Abstract

A major area of interest in condensed matter physics is the way electrons in correlated electron materials can selforganizeinto ordered states, and a particularly intriguing possibility is that they spontaneously choose apreferred direction of conduction. The correlated electron metal Sr3Ru2O7 has an anomalous phase at low temperaturesthat features strong susceptibility toward anisotropic transport. This susceptibility has been thought toindicate a spontaneous anisotropy, that is, electronic order that spontaneously breaks the point-group symmetryof the lattice, allowing weak external stimuli to select the orientation of the anisotropy. We investigate further bystudying the response of Sr3Ru2O7 in the region of phase formation to two fields that lift the native tetragonalsymmetry of the lattice: in-plane magnetic field and orthorhombic lattice distortion through uniaxial pressure. The response to uniaxial pressure is surprisingly strong: Compressing the lattice by ~0.1% induces an approximately100% transport anisotropy. However, neither the in-plane field nor the pressure phase diagrams are qualitativelyconsistent with spontaneous symmetry reduction. Instead, both are consistent with a multicomponent orderparameter that is likely to preserve the point-group symmetry of the lattice, but is highly susceptible to perturbation.