Magnetic properties of Sr0.78Y0.22CoO3−δ under high pressure

We have investigated the temperature dependence of magnetization in a polycrystalline sample of Sr0.78Y0.22CoO3−δ under high pressure of up to 0.52 GPa. It turned out that this sample shows the large pressure dependence of Tc and magnetization. We found that the pressure derivative of TC, dTC/dP, is −432 K/GPa for P 0.1 GPa. From comparison with Ca-substituted samples, we evaluate the bulk modulus to be 83 GPa. The large pressure dependence is attributed to the small bulk modulus of this oxide and sensitive spin states of Co ions.