Systematic 63Cu NQR and 89Y NMR study of spin dynamics in Y1-zCazBa2Cu3Oy across the superconductor-insulator boundary

A systematic investigation of Y1-zCazBa2Cu3Oy was presented using ⁸⁹Y nuclear magnetic resonance (NMR) and ⁶³Cu nuclear quadrupole resonance (NQR). The similarity in the paramagnetic spin dynamics between Y1-zCazBa2Cu3O6.0 and La2-xSrxCuO4 for an equivalent nominal hole concentration was demonstrated. As more holes were doped into the CuO2 plane by increasing the oxygen concentration, a spin gap appeared. It was also found that the low frequency spin fluctuations were enhanced by disorder effects caused by Ca doping.