NMR/NQR in the antiferromagnetic parent compounds of high-temperature superconductors

We review nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) experiments performed in La2CuO4, YBa2Cu3O6, and Ca(Sr)CuO2 which ar e the antiferromagnetic parent compounds of some high-temperature supercond uctors. Both antiferromagnetic and paramagnetic phases are considered. The following topics are discussed: (1) Measurement and calculation of the subl attice magnetization (and hence the magnon excitation spectrum) in these co mpounds and its critical behavior; (2) low energy excitations in the antife rromagnetic phase of Ca(Sr)CuO2; (3) various crossovers in Ca(Sr)CuO2; (4) bilayer coupling in YBa2Cu3O6. (C) 2001 Elsevier Science B.V. All rights re served.