English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Measurements of the magnetic irreversibility line and time-logarithmic decayof the magnetization are described for three $Fe_{2}O_{3}$ samples composed ofregular amorphous, acicular amorphous and crystalline nanoparticles. Therelaxation rate is the largest and the irreversibility temperature is thelowest for the regular amorphous nanoparticles. The crystalline materialexhibits the lowest relaxation rate and the largest irreversibilitytemperature. We develop a phenomenological model to explain the details of theexperimental results. The main new aspect of the model is the dependence of thebarrier for magnetic relaxation on the instantaneous magnetization andtherefore on time. The time dependent barrier yields a natural explanation tothe time-logarithmic decay of the magnetization. Interactions between particlesas well as shape and crystalline magnetic anisotropies define a new energyscale that controls the magnetic irreversibility. Introducing this energy scaleyields a self-consistent explanation of the experimental data.Comment: RevTex, 16 JPEG figures, to appear in PR

Magnetic irreversibility and relaxation in assembly of ferromagnetic nanoparticles