Internal friction evidence of uncorrelated magnetic clusters in electron-doped manganite Sr0.8Ce0.2MnO3

Electron-doped manganite Sr_0.8Ce_0.2MnO₃ has been systematically investigated by X-ray diffraction, electronic transport, magnetic, internal friction, and Young's modulus experiments. The X-ray diffraction result indicates that the compound remains tetragonal (I4/mcm) structure at room temperature. Due to the strong Jahn–Teller (JT) distortion, the ground state is antiferromagnetic (AFM) insulator. Below 20 K, a spin-glass (SG) state dominates at low temperatures. In the paramagnetic (PM) region, an internal friction peak at around 250 K, which is characteristic of relaxation, has been observed. Under applied magnetic field, the internal friction peak moves to higher temperature, which is suggested to originate from the formation of ferromagnetic (FM) clusters in PM region. In addition, the softening of Young's modulus in the vicinity of AFM transition temperature is interpreted in terms of the strong electron–phonon interaction.