Magnetically and thermally modulated microwave absorption in Y1Ba2Cu3O7-x single crystal near T-c

The microwave absorption R in the Y1Ba2Cu3O7-x single crystals was investig ated near T-c approximate to 92K and in the external magnetic field 0 < H l ess than or equal to 9kOe kOe. A modified ESR spectrometer was used in the experiment. The method of temperature modulation, along with the usual meth od of magnetic-field modulation, was first applied in studying of the micro wave response of these crystals. Peaks in the temperature dependencies of t he signals partial derivative R/partial derivative H and partial derivative R/partial derivative T observed in the vicinity of T-c were differently sh aped and shifted one with respect to another. The evolution of the peaks wi th variation of the magnetic field and angle theta between H and the c-axis was traced. It has been shown that the observed difference of the temperat ure dependencies of the derivatives partial derivative R/partial derivative H and partial derivative R/partial derivative T occurs due to the field-in duced broadening of the superconducting transition, which is inherent in th e high-T-c superconductors.