Magnetization Study of the Superconducting Pyrochlores AOs2O6 (A=Rb, K) under Pressure

Dc magnetization has been observed as a function of temperature for superconducting β‐pyrochlore oxides KOs2O6 (TC=9.6 K) and RbOs2O6 (TC=6.3 K) under pressure p < 4 GPa. It is found that TC for KOs2O6 increases and shows a maximum of 10 K at p=0.5 GPa, whereas TC for RbOs2O6 shows a monotonic increase and reaches 8.7 K at p=3.9 GPa. The TC − p curves suggest that the relationship between TC and lattice constant in these compounds is different from each other.