μμSR studies of the interplay of magnetic spin stripe order with superconductivity in transition metal oxides

In this work we review muon spin relaxation experiments on the layered La2−xSrxNiO4 nickelate as well as La2−xBaxCuO4 and La2−xSrxCuO4 cuprate systems to examine spin stripe order. In particular, the interplay of stripe order with superconductivity in Nd and Eu doped La2−xSrxCuO4 cuprates is discussed. Detailed studies of the electronic phase diagrams as well as the magnetic and superconducting order parameters for different rare-earth and Sr doping levels in La2−x−yREySrxCuO4 revealed the strong correlation of static spin stripe order with the structural distortion in the low temperature tetragonal (LTT) phase and the competition with the superconducting ground state. High magnetic field studies demonstrate the nearly degenerate ground state energy of the different electronic phases. Slow transverse fluctuations of the charge stripes are found in nickelates and cuprates at low temperatures.