Direct measurement of superparamagnetic fluctuations in monodomain Fe particles via neutron spin-echo spectroscopy

Citation
H. Casalta et al., Direct measurement of superparamagnetic fluctuations in monodomain Fe particles via neutron spin-echo spectroscopy, PHYS REV L, 82(6), 1999, pp. 1301-1304
Citations number
16
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW LETTERS
ISSN journal
00319007 → ACNP
Volume
82
Issue
6
Year of publication
1999
Pages
1301 - 1304
Database
ISI
SICI code
0031-9007(19990208)82:6<1301:DMOSFI>2.0.ZU;2-3
Abstract
Using the technique of neutron spin-echo spectroscopy, we have conducted a direct measurement of the superparamagnetic relaxation of nanoscale, magnet ic monodomain iron particles in the time range between 0.01 and 160 nsec an d for momentum transfers q between 0.035 and 0.15 Angstrom(-1) Using a phen omenological model which includes the effect of a particle size distributio n, we are able to determine the temperature T and q dependence of the longi tudinal superspin relaxation time spanning 4 orders of magnitude. We find t hat for T less than or similar to 40 K, interparticle correlations affect t he longitudinal superspin Fluctuations. [S0031-9007(98)08356-2].