Strain and Vector-Magnetic-Field Tuning of the Anomalous Phase in Sr3Ru2O7

Symmetry is a basic paradigm for analysis of problems in solid state physics, and to controllably break point-group symmetries is a powerful probe of novel forms of order. In this work, we apply two methods, controlled lattice strain and vector magnetic field, to study a well-known correlated electron phase that appears at low temperatures in the layered material Sr3Ru2O7. This phase responds strongly to C4-symmetry-breaking fields, suggesting spontaneous C4 symmetry breaking. However, in this work we find that the data are more easily explained with microscopic coexistence of two orthogonal order parameter components than spontaneous symmetry breaking. The techniques presented in this work will be relevant for other systems where spontaneous C4 symmetry breaking is suspected.