MAGNETIC-FIELD DEPENDENT MICROWAVE-ABSORPTION IN A SM2-XCEXCUO4 SINGLE-CRYSTAL

We have performed magnetically modulated microwave absorption (MAMMA) measurements on a superconducting Sm2-xCexCuO4 single crystal, with th e DC magnetic field parallel to the c-axis. Temperature sweeps of the MAMMA signal show an irreversible behavior after ZFC and FC processes. Similarly, isothermal magnetic field sweeps also show a region of hys teretic behaviour. In both cases, the irreversibility lines are coinci dent. This work shows that the MAMMA technique is well suited to deter mine the irreversibility line and can provide new insight into the nat ure of flux dynamics.