Disorder-sensitive phase formation linked to metamagnetic quantum criticality

Condensed systems of strongly interacting electrons are idea[ for the study of quantum complexity. It has become possible to promote the formation of new quantum phases by explicitly tuning systems toward special low-temperature quantum critical points. So far, the clearest examples have been appearances of superconductivity near pressure-tuned antiferromagnetic quantum critical points. We present experimental evidence for the formation of a non-superconducting phase in the vicinity of a magnetic field-tuned quantum critical point in ultrapure crystals of the ruthenate metal Sr3Ru2O7,and we discuss the possibility that the observed phase is due to a spin-dependent symmetry-breaking Fermi surface distortion.