Temperature-dependence of low-energy spin excitation in electron-doped high-Tc superconductor Pr1-xLaCexCuO4

We studied the temperature-dependences of low-energy spin fluctuations in electron-doped high-Tc cuprates, Pr1-xLaCexCuO4 (PLCCO) for both superconducting (SC) and long range antiferromagnetic (AF) ordered phases. We clarified the different thermal evolution of local spin susceptibility χ″(ω) between the AF and SC samples. For the former sample (x=0.07), χ″(ω) is nearly temperature-independent in the AF ordered state. On the other hand, for the latter samples (x=0.11 and 0.15), the spectral weight in lower-energy region decreases and the peak-energy in χ″(ω) shifts toward high-energy region upon heating. Such different thermal evolution of spin fluctuations between the AF and SC phases is discussed from a viewpoint of degradation of spin correlations by electron-doping which reduces in-plane averaged magnetic interaction.