Effect of pressure on magnetic and transport properties of CaMn _1-xRu_xO₃ (x=0-0.15): Collapse of ferromagnetic phase in CaMn_0.9Ru_0.1O₃

Magnetic and transport properties of CaMn_1-xRu_xO ₃ (x=0;0.1;0.15) perovskites were investigated in the temperature range 4.2-280 K, magnetic fields up to 15 kOe and hydrostatic pressure up to 12 kbar. It was found that for a substitution of x=0.1, an applied pressure of 12 kbar shifts up the magnetic transition temperature by ∼14 K and simultaneously drastically suppresses the ferromagnetic metallic phase. For x=0.15, the application of pressure reduces transition temperature by about -0.28 K/kbar and suppresses the FM phase in a less pronounced manner. Observed changes in resistivity and magnetoresistance of CaMn_0.9Ru _0.1O₃ are described by suppression of the double-exchange interactions under pressure. They are discussed in the context of the phase separation and valency effects.