Effects of Doping on the Field-dependent Phases of Ca$_{3}$Ru$_{2}$O$_{7}$

The double-layer ruthenate Ca$_{3}$Ru$_{2}$O$_{7}$ has been shown to possess a rich magnetic-field dependence for fields applied in the a-b plane. In its ground state, Ca$_{3}$Ru$_{2}$O$_{7}$ is an antiferromagnetic insulator, turning metallic above T$_{MI}$ = 48 K and paramagnetic above T$_{N}$ = 56 K. Light doping with Sr (r = 1.18 \r{A} vs. r = 1.00 \r{A} for Ca) causes a reduction in the anisotropy field due to the change in lattice parameter along the c-axis, thereby giving us a bandwidth control, while doping with trivalent La (r = 1.03 \r{A}) not only alters the bandwidth but also adds an extra electron for filling control. Using Raman scattering we map out the orbital, magnetic, and conducting phases by studying the field- and temperature-dependence of the magnetic and vibrational spectra. In this talk we describe the role Sr- and La- doping has on the field dependent phases of (Ca,Sr,La)$_{3}$Ru$_{2}$O$_{7}$. Work supported by NSF DMR02-44502, NSF DMR02-40813, and DOE DEFG02-91ER45439.