Zn-induced wipeout effect on Cu NQR spectra in La 2- x Sr x Cu 1- y Zn y O 4

Abstract We report a systematic study of Zn-substitution effect on Cu NQR spectrum for high Tc superconductors La2−xSrxCu1−yZnyO4 from carrier-underdoped to -overdoped regimes (polycrystalline samples, x=0.10, 0.15, and 0.20). We observed no appreciable wipeout effect for the overdoped samples, a gradual and partial wipeout effect below about 80 K for the optimally doped ones, and very abrupt and full wipeout effect below about 40 K for the underdoped ones. The wipeout effect indicates a highly enhanced spectral weight of Cu spin fluctuations at a low frequency. We associate the wipeout effect with a Zn-induced local magnetism far above 40 K and with a localization effect below 40 K.