Magnetism dynamics driven by phase separation in Pr-doped manganite thin films: A ferromagnetic resonance study

We performed ferromagnetic resonance measurements of a ${({\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Pr}}_{x})}_{1\ensuremath{-}y}{\mathrm{Ca}}_{y}\mathrm{Mn}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ with $x=0.52\ifmmode\pm\else\textpm\fi{}0.05, y=0.23\ifmmode\pm\else\textpm\fi{}0.04$, and $\ensuremath{\delta}=0.14\ifmmode\pm\else\textpm\fi{}0.10$ thin single crystalline film which, in combination with micromagnetic simulations, reveal three temperature regions consistent with (i) a ferromagnetic-paramagnetic transition in which ferromagnetic domains nucleate and grow, (ii) followed by a filamentary fluidlike percolation of magnetic domains exhibiting dynamic processes and finally, iii) the existence of a blocking temperature below which the magnetism is a metastable glassy-like state with strong decoherence of the uniform resonance mode. Our results suggest a strain-liquid to strain-glass spin order transition in which the magnetism and fluidlike dynamics of the separated phases freeze at low temperatures. We show the magnetism dynamics depend strongly on the phase-separated state and morphology of the magnetic domains suggesting a route to control of phase separation and realization of spintronic and magnonic devices.