ACOUSTOELECTRIC EFFECT OF SUPERCONDUCTING YBA2CU3O7-X FILMS

An acoustoelectric effect has been studied in a layered structure consisting of YZ-LiNbO3 and a superconducting YBa2Cu3O7-x film. At 300 K the acoustic voltage has a positive sign, i.e., it corresponds to a hole conductivity. At T less-than-or-equal-to T(c) = 98 K the acoustic voltage decreases sharply to zero (at 95 K), changes sign, and increases in absolute value to a maximum at T = 90 K (R = 0). It then decreases to zero at 78-81 K.