μ+ SR studies on Sr2CuO2Cl2, La2CuO4 and Nd2CuO4: 2-d magnetism, local fields and muon sitesSR studies on Sr2CuO2Cl2, La2CuO4 and Nd2CuO4: 2-d magnetism, local fields and muon sites

We compare the temperature dependence of the zero-field muon spin precession frequency observed in Sr2CuO2Cl2 and La2CuO4 below the Néel temperature with a 2-d Heisenberg model with an additional small anisotropy. Good agreement of the observed results with this model reflects the highly 2 dimensional magnetic properties of these cuprates. The measured local fields are compared with a simple calculation of dipolar fields in the crystal to search for muon site locations. Our results provide evidence that the muon sites are related to the oxygen atoms in these compounds.