摘要
In this work, we attempt to investigate the relation between the hole-doping effect and electron spin resonance (ESR) spectra in the series of (Tl0.5Pb0.5)Sr2(Ca1−xYx)Cu2O7 high-Tc superconductors. The spin signal is absent for x=0.2 which is the optimal doping for obtaining a maximum Tc, while the ESR signals recover for the underdoped and overdoped samples. This result can be expressed by the slowing down of the superexchange force between next-neighboring copper ions which retrieve their native local moments by the increase or decrease of hole doping. The unexpected vanish of ESR spectra for the antiferromagnetic insulator at x=0.9 implicates a highly correlated spin fluctuation in the (Tl0.5Pb0.5)Sr2(Ca1−xYx)Cu2O7 system.