Size Effect on LuMn₂O₅ Nanorods

LuMn₂O₅ multiferroic nanorods were fabricated using the hydrothermal method with three sizes of diameters (( L_C ) × axial lengths of 66(22) nm × 18(5) nm, 78(38) nm × 22 (9) nm, and 91(35) nm × 20(7) nm, as determined by the field emission transmission electron microscope and selection area electron diffraction. A small ferrimagnetic (FIM) peak was obtained at 27 K from the nanorods with ( L_C ) = 66 and 78 nm, and the 91 nm sample exhibited FIM behavior below 43 K. All the samples had a hysteresis loop at 2 K. The fitted μ_eff (effect moment), T_so (spin-orbit interaction), and the coercively greatly increased with size to ( L_C ) = 91 nm. These results reveal that the size importantly affects the magnetic properties between ( L_C ) = 78 and 91 nm. Raman spectra were obtained at various temperatures to determine the effects of the size on the ( L_C ) = 78 and 91 nm samples. The red-shift of the A_g+ B_1g mode increased with temperature only for the 91 nm sample, revealing that the interaction between the Mn-O bonds is more sensitive to temperature in larger LuMn₂O₅ nanorods.