MICROWAVE DIELECTRIC RESONANCE IN THE YBA2CU3O7 SINGLE-CRYSTAL

First observations of the microwave dielectric resonance in the single crystal YBa2Cu3O7 are presented. With the HTSC single crystal inserte d into a microwave (f similar to 9 GHz) resonator we observe the appea rance of the new intense and broad transmission band. Intensity of thi s band exhibits remarkable temperature hysteresis. The observed birefr ingence is the intrinsic property of the HTSC material resulting from the spatial dispersion and nonlinearity of HTSC electric properties du e to the metal-insulator-type instability.