Evolution of magnetic state with nanoparticle size in electron-doped cuprate Eu _1.85 Ce _0.15 CuO _{4+ <i>α</i> − <i>δ</i>}

Abstract This study explores the synthesis and characterization of electron-doped cuprate Eu 1.85 Ce 0.15 CuO 4+- δ nanoparticles with varying particle sizes, produced through controlled sintering conditions. X-ray Diffraction (XRD) analysis confirms that all samples exhibited a single-phase tetragonal T ’ crystal structure, with lattice parameters in the range of a = 3.9014−3.9031 Å and c = 11.9019−11.9071 Å. Field Emission Scanning Electron Microscopy (FESEM) reveals particle sizes ranging from 56 nm to 169 nm, demonstrating a correlation between particle size and sintering temperature. Energy Dispersive x-ray (EDX) analysis indicates that the elemental composition closely matches the stoichiometric calculations, though minor deviations were observed due to the technique limitations. Magnetic measurements using a superconducting quantum interference device (SQUID) confirm the absence of superconductivity in all samples down to 2 K. A transition is observed from paramagnetic behavior in the 169 nm sample to the coexistence of spin-glass and ferromagnetic states when particle size is reduced to 136 nm or smaller. These findings provide valuable insights into the relationship between particle size and magnetic properties in the electron-doped cuprate system, highlighting the significant role of size in modulating these behaviors.