Investigation of magnetic properties in high Tc oxides by muon spin rotation

This paper describes experiments in which local magnetic fields are investigated by polarized positive muons in a variety of high Tc oxides. Two apparently separate subjects are involved: first, the static and dynamic properties in the magnetically ordered phase, namely the spontaneous magnetization, its temperature dependence, and their relation to the ''''extra'''' carriers (holes or electrons); secondly, the penetration depth in the superconducting phase with particular reference to YBa2Cu3O6.2 and YBa2(Cu1-zZnz)3O7 in which hole concentration and effective mass can be separately varied by removing oxygen and substituting Cu by Zn, respectively. (author)