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

We have performed magnetic measurements on a diluted system of gamma-Fe2O3nanoparticles (~7nm), and on a ferritin sample. In both cases, the ZFC-peakpresents a non-monotonic field dependence, as has already been reported in someexperiments,and discussed as a possible evidence of resonant tunneling. Withinsimple assumptions, we derive expressions for the magnetization obtained in theusual ZFC, FC, TRM procedures. We point out that the ZFC-peak position isextremely sensitive to the width of the particle size distribution, and givesome numerical estimates of this effect. We propose to combine the FCmagnetization with a modified TRM measurement, a procedure which allows a moredirect access to the barrier distribution in a field. The typical barriervalues which are obtained with this method show a monotonic decrease forincreasing fields, as expected from the simple effect of anisotropy barrierlowering, in contrast with the ZFC results. From our measurements ongamma-Fe2O3 particles, we show that the width of the effective barrierdistribution is slightly increasing with the field, an effect which issufficient for causing the observed initial increase of the ZFC-peaktemperatures.Comment: LaTeX file 19 pages, 9 postscript figures. To appear in Phys. Rev. B  (tentative schedule: Dec.97

Nonmonotonic field dependence of the zero-field cooled magnetization peak in some systems of magnetic nanoparticles