The role of disorder in Fe-doped CMR manganites as explored by μSR spectroscopy

A study on the effect of Fe doping on the magnetic properties of La0.7Pb0.3Mn1-xFexOx, x=0 and x=0.2 perovskites is conducted using muon spectroscopy and macroscopic static magnetization measurements. For x=0, magnetization curves show a clear ferromagnetic component while a 20% Fe doping leads to the appearance of a kink in zero-field curves at low temperatures, attributed to progressive spin freezing together with a reduction of the ferromagnetic component. On dynamic grounds, we show that this effect translates into the appearance of non-exponential relaxation as Tc is crossed from above.