Magnetic moment relaxation studies by swept and pulsed microwave technique in LaSrCuO epitaxial thin film

We report magnetic relaxation experiments in a LaSrCuO epitaxial thin film under the action of crossed rf and dc magnetic fields. By applying a swept-frequency technique we found discontinuities in the relaxation curves in the form of a single jump at the lowest temperatures and dc magnetic fields, and sharp peaks either near Tc or for the largest dc magnetic fields. Maxima in the temperature and dc magnetic field dependences of the maximum output voltage signal of the SQUID magnetometer used for the magnetic measurements are observed in a defined temperature range when a pulsed microwave technique is used.