Ultrasonic attenuation anomalies of n-type superconductor Pr2−xCexCuO4

Abstract

Pr[Formula: see text]Ce[Formula: see text]CuO4 ([Formula: see text] = 0 and 0.15) samples were prepared via solid state reaction. Pr2CuO4 sample is insulating while Pr[Formula: see text]Ce[Formula: see text]CuO4 sample exhibited an onset critical temperature, [Formula: see text] of 21 K. The temperature dependences of ultrasonic attenuation in these polycrystalline n-type superconductor Pr[Formula: see text]Ce[Formula: see text]CuO4 ([Formula: see text] = 0 and 0.15) samples have been measured between 80 K and 300 K using longitudinal and shear waves by pulse-echo-overlap method with frequencies between 5 MHz and 10 MHz. For the longitudinal mode, a pronounced attenuation peak around 200 K was observed in Pr2CuO4, but it is not observed in the superconducting material Pr[Formula: see text]Ce[Formula: see text]CuO4. For the shear mode, no pronounced attenuation peaks were observed in the samples. It is suggested that the attenuation peak in the [Formula: see text] = 0 sample at 200 K is due to the weak structural distortion induced by the magnetic transition.