(M=Cr, Mn and Fe)*

The comparable magnitudes of the Coulomb interaction and 4d-bandwidth can leave ruthenates precariously balanced on the border between metallic and insulating behavior, and/or on the verge of long-range magnetic order. Ca₂RuO₄ is an antiferromagnetic (AFM) Mott insulator with Neel temperature at T_N = 110 K and a first-order metal-insulator transition at T_MI = 357 K. It is recognized that Ca₂RuO₄ and its derivatives are highly sensitive to the lattice degrees of freedom. Here we report that application of modest pressure (< 2.5 GPa) readily destabilizes the AFM Mott state and precipitates a ferromagnetic metallic state at low temperatures in Ca₂Ru_1-xM_xO₄ (M=Cr, Mn and Fe). Transport and magnetic properties including neutron diffraction at pressure will be presented and discussed along with other related systems.