The Library
Quantifying exchange coupling in segregated granular materials
Tools
Morrison, C., Saharan, Lalita, Ikeda, Y., Takano, K., Hrkac, Gino and Thomson, T. (Thomas) (2013) Quantifying exchange coupling in segregated granular materials. Journal of Physics D: Applied Physics, Volume 46 (Number 47). Article number 475002. doi:10.1088/0022-3727/46/47/475002 ISSN 0022-3727.
|
Text
WRAP_Morrison_1174252-px-160114-quantifyingexchangecoupling-02-09-13 (1).pdf - Accepted Version Download (1070Kb) | Preview |
Official URL: http://dx.doi.org/10.1088/0022-3727/46/47/475002
Abstract
The volume of a magnetic grain, together with its anisotropy, determines the probability of thermally activated reversal. Thus for grain volume distributions where the median volume is close to the superparamagnetic limit there will be a sub-set of grains which are either superparamagnetic on the time scale of a typical magnetic measurement (10 s), or the reverse due to magnetostatic fields from surrounding grains. We use this effect to probe exchange coupling in segregated granular materials, using CoCrPt–SiOx granular recording media as model systems. As the film thickness is reduced below 10 nm, the remanent magnetization of these films decreases, due to thermal activation and magnetostatic reversal. Varying film thickness and temperature allows us to thermally select a population of grains that contribute to the measurement. Exchange coupling is characterized by the angle dependence of remanent coercivity where we associate a breaking of symmetry from the Stoner–Wohlfarth model towards the Kondorsky model as a measure of the incoherency of reversal. Combining these models allows an estimate to be made of the volume fraction of grains that are exchange coupled and we find that, for well segregated CoCrPt–SiOx media, approximately 8% of the magnetic volume undergoes some degree of exchange coupling.
Item Type: | Journal Article | ||||
---|---|---|---|---|---|
Subjects: | Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General) |
||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||
Library of Congress Subject Headings (LCSH): | Magnetic couplings, Anisotropy, Granular materials | ||||
Journal or Publication Title: | Journal of Physics D: Applied Physics | ||||
Publisher: | IOP Publishing | ||||
ISSN: | 0022-3727 | ||||
Official Date: | 2013 | ||||
Dates: |
|
||||
Volume: | Volume 46 | ||||
Number: | Number 47 | ||||
Page Range: | Article number 475002 | ||||
DOI: | 10.1088/0022-3727/46/47/475002 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access | ||||
Date of first compliant deposit: | 26 December 2015 | ||||
Date of first compliant Open Access: | 26 December 2015 | ||||
Funder: | Engineering and Physical Sciences Research Council (EPSRC) | ||||
Grant number: | EP/G032440/1, EP/G032300/1 (EPSRC) |
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |
Downloads
Downloads per month over past year