Size effects in epitaxial films of magnetite

Studies of the Magnetite Nanoparticles by Means of Mössbauer Spectroscopy

“…The obtained values of isomer shift and quadrupole splitting are very close to the bulk parameters. The hyperfine magnetic fields are slightly lower than in bulk [7] which agree with the data published in [5,2]. The third sextet has hyperfine magnetic field, isomer shift, and quadrupole splitting not belonging to either A or B position.…”

“…The analysis showed that β = 1.10 ± 0.05, 1.41 ± 0.05, and 1.66 ± 0.05 for 0.5 h, 1 h, and 3 h time of reaction, respectively. All these values are smaller than β = 1.94 obtained for stoichiometric bulk magnetite [2]. It can be concluded that the longer reaction time improves the stoichiometry of obtained nanoparticles.…”

“…The first one with higher hyperfine magnetic field belongs to A site and the second one with smaller hyperfine field assigned to B site. In stoichiometric bulk magnetite the ratio between intensity of A and B sextets is equal to β = 1.94 [2] due to different recoil-free factors of Fe in A and B positions. This parameter is sensitive to the stoichiometry of the magnetite and to the diameter of the particle [2,3].…”

“…In stoichiometric bulk magnetite the ratio between intensity of A and B sextets is equal to β = 1.94 [2] due to different recoil-free factors of Fe in A and B positions. This parameter is sensitive to the stoichiometry of the magnetite and to the diameter of the particle [2,3]. The excess of oxygen leads to the creations of the vacancies in the B site.…”

Magnetism in nanometer-thick magnetite

“…While some reports state than magnetite films close to 3 nm thick present a well defined magnetic structure, 20,22,23,29,30 others indicate that clear signs of superparamagnetic behavior are observed at the same thickness. 12,[31][32][33][34] We grow 1-nm-thick, micron-wide, magnetite crystals on ruthenium 25 using reactive molecular beam epitaxy (i.e., depositing iron in a background of oxygen) while monitoring the growth in real time by low-energy electron microscopy (LEEM 27 ). We show by imaging their individual magnetization patterns and their x-ray magnetic circular dichroism (XMCD) spectra that they are ferrimagnetic.…”