INFLUENCE OF OXYGEN ORDERING ON THE MAGNETIC PENETRATION DEPTH IN S-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.93)(X (0.39)

The influence of room-temperature oxygen ordering on the magnetic pene tration depth lambda in the YBa2Cu3O6+x compound was studied for a wid e range of the oxygen content (0.39 less than or equal to x less than or equal to 0.93). Oxygen ordering induces a lambda decrease, resultin g from the enhancement of the hole density in the CuO2-planes. The sup erconducting transition temperature T-c attains a maximum at x approxi mate to 0.9, while the density of the carriers responsible for superco nductivity continues to increase monotonically. Oxygen ordering leads to the formation of a 60 K plateau in the T-c versus 1/lambda(2) propo rtional to n/m dependence.