Investigations on temperature-dependent magnetic properties and magnetic thermal stability of magnesium ferrite (MgFe₂O₄) nanoparticles

Low temperature magnetization measurements of citrate precursor-synthesized magnesium ferrite nanoparticles (MFNPs) of - 27 nm were conducted by progressively lowering the temperature from 300 K to 100 K. Hysteresis curves revealed unsaturated magnetization even at +/- 15 kOe, attributed to surface spins. Specific saturation magnetization (sigma s) and coercivity (Hc) experienced an increase from 26.46 emu/g (300 K) to 34.79 emu/g (100 K), and from 92 Oe (300 K) to 187 Oe (100 K), respectively. Specific remanence magnetization (sigma r) rose from 5.58 emu/g (300 K) to 10.14 emu/g (100 K), indicating a notable shift in magnetic behavior. Effective anisotropy constant (Keff) showed significant growth from 2474.14 erg/g (300 K) to 6635.04 erg/g (100 K), highlighting low magnetocrystalline anisotropy at room temperature. The rise in magnetic moment (nB) from 0.95 Am2 at 300 K to 1.25 Am2 at 100 K indicates improved magnetic alignment and stability, particularly at lower temperatures. Correlation analysis revealed strong negative curvilinear correlations between magnetic properties and temperature. Extrapolation estimated the blocking temperature (-573 K), coercivity at 0 K (-249 Oe), and Curie temperature (-660 K). These results suggest promising applications in space technology, underscoring the enhanced sensitivity of MFNPs to external magnetic fields in cold environments.