Ultrasonic study on YBa2(Cu1−xZnx)3O7−δ

Ultrasonic attenuation and velocity measurements in the megahertz frequency range have been performed on YBa2(Cu1−xZnx)3O7−δ (x = 0,0.01,0.02,0.03,0.04 and 0.05) by a pulse–echo method below 200 K in magnetic fields up to 14 T. Three attenuation peaks located at 70, 130 and 170 K (P1, P2 and P3) were observed. From the Zn concentration, frequency, magnetic field and oxygen content dependences of the three peaks, it is suggested that P1 is associated with the short-distance jump of polarons formed by holes in the CuO2 planes, P2 is ascribed to the jump of apical oxygen atoms between off-centred positions induced by the Jahn–Teller effect and P3 is related to the jump of oxygen atoms in the Cu–O chains, respectively.