Field-modulated microwave absorption in thin YBaCuO films

Hysteretic behaviour of field-modulated microwave absorption is investigate d in thin YBaCuO films with thickness d approximate to 50 or 400 nm, by sca nning the external magnetic field in opposite directions, and in constant m agnetic fields when the specimen is rotated. A negative hysteresis loop of field-modulated microwave absorption is detected in the films with d approx imate to 50 nm. An addition signal corresponding to decrease of the absorpt ion when the field is parallel to the film surface is found. (C) 2000 Elsev ier Science B.V. All rights reserved.