Electronic Homogeneity in the Overdoped Regime of the Electron-Doped High-T_c Superconductors

In order to investigate the electronic homogeneity in electron-doped high-T_c cuprates, magnetization and specific heat measurements have been performed for Pr_1-xLaCe_xCuO₄ single crystals with x = 0.13 – 0.17. It has been found from the magnetization curve that the hysteresis is relatively small and that the so-called second magnetization peak is absent for every x. Moreover, the Sommerfeld constant in the ground state has shown HlnH dependence on magnetic field H for every x, suggesting that the superconductivity is not pure but dirty. These results are in contrast to those observed in the overdoped regime of hole-doped La_2-xSr_xCuO₄ where an inhomogeneous superconducting state is formed in spite of the superconductivity being pure. Therefore, it has been concluded that a rather homogeneous electronic state is realized in the electron-doped cuprates, suggesting different electronic states between hole- and electron-doped cuprates