Magnetic Field Induced Phases of Ca$_{2}$RuO$_{4}$ and Ca$_{3}$Ru$_{2}$O$_{7}$

We present a Raman scattering study of the magnetic field induced phases in the layered ruthenates Ca$_{2}$RuO$_{4}$ and Ca$_{3}$Ru$_{2}$O$_{7}$. Single-layer Ca$_{2}$RuO$_{4}$ has an antiferromagnetic ground state, is a paramagnetic (PM) insulator above T$_{N}$ = 113 K and is a PM metal above T$_{MI}$ = 357 K, while double-layer Ca$_{3}$Ru$_{2}$O$_{7}$ has an antiferromagnetic insulating ground state, is metallic above T$_{MI}$ = 48 K, and is paramagnetic above T$_{N}$ = 56 K. Applied fields oriented in the a-b planes of both these materials produce dramatic changes to both the magnetic and vibrational spectra; these changes are associated with field-induced changes in the Ru orbital populations of these materials. In this talk, we compare the field induced orbital, magnetic, and conducting phases observed in Ca$_{2}$RuO$_{4}$ and Ca$_{3}$Ru$_{2}$O$_{7}$. *Work supported by NSF DMR02-44502, NSF DMR02-40813, and DOE DEFG02-91ER45439.