Magnetic Properties of Small Magnetite Nanocrystals

Abstract

This paper focuses on the study of the magnetic properties of 9 nm magnetite nanocrystals. XRD and TEM measurements indicate the presence of crystalline particles, with a fraction of them only partially crystallized or highly defective. The analysis of the temperature dependence of the zero-field-cooled/field-cooled magnetization and of the thermoremanent magnetization provides evidence of the existence of three magnetic regimes: a high temperature regime (300-100 K), an intermediate regime (100-20 K), and a low temperature regime (below 20 K). The characteristics of such regimes are discusse

The interplay between single particle anisotropy and interparticle interactions in ensembles of magnetic nanoparticles

“…Magnetic nanoparticles (NPs) are complex physical objects that are interesting from both fundamental [1][2][3][4] and technological points of view (e.g., MRI, 5 hyperthermia, 6 drug delivery, 5,7 catalysis, 8 microwave applications 9 ). For magnetic monodomain particles with uniaxial anisotropy and easy axis alignment in the direction of the external field m 0 H, the energy can be written as:…”

Seeded growth of ferrite nanoparticles from Mn oxides: observation of anomalies in magnetic transitions

“…With the decrease of particle size, charge ordering is known not as efficient and not as fast as in the bulk magnetite, which makes a smooth decrease of magnetic susceptibility around the transition. 39,40 Also noteworthy in M-T curve of Fe 3 O 4 NPs is the small broad mound centered at 35 K in ZFC measurement. In Fe 3 O 4 NPs with a sharp decrease of magnetization such as in our study, this broad mound is regularly observed.…”

“…In Fe 3 O 4 NPs with a sharp decrease of magnetization such as in our study, this broad mound is regularly observed. 40 One reason would be the glass-like transition with a sharp decrease of magnetization, which is caused by electrical low temperature tunnelling. 41 The other assumption is that there is a partial surface oxidation in Fe 3 O 4 .…”

Selective Magnetic Evolution of MnxFe1–xO Nanoplates

“…In many AFM/FM materials, this broad transition at low temperature is observed. 51,52 With the hysteresis shift in M exists. There is AFM-FM interaction between them, and this interaction causes magnetic transition at around 60 K (Figure 6b), which is clearly observed in the derivative curves ( Figure 7).…”