Microwave spectroscopy of 3D-XY critical charge dynamics in electron-doped La2-xCexCuO4 superconducting thin films

Dynamic fluctuation effects of electron-doped La2-xCexCuO4 superconducting thin films for a wide range of the Ce concentration (x=0.075 to 0.15) are studied through the microwave spectroscopic measurements in zero magnetic field. Dynamic scaling analysis of the fluctuation-induced microwave conductivity shows that the three-dimensional (3D) XY critical behavior is observed in a wide range of electron dopings, in contrast to our previous results on the hole-doped La2-xSrxCuO4 thin films where three kinds of critical charge dynamics and two kinds of dimensional crossovers were observed by hole doping. Our results clearly indicate that the critical behaviors between hole-doped and electron-doped regions in the phase diagram of high-Tc cuprates are not symmetric intrinsically. Thus, correct theories describing high-temperature superconductivity in cuprates should meet this criterion.