  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.
