Release Time:2019-03-12  Hits:

Indexed by: Journal Article

Date of Publication: 2018-05-01

Journal: AIP ADVANCES

Included Journals: Scopus、CPCI-S、EI、SCIE

Volume: 8

Issue: 5

ISSN: 2158-3226

Abstract: We report results of magnetic hysteresis scaling of minor loops for cobalt nanoparticles with variable mean particle size of 53 and 95 nm. A power-law scaling with an exponent of 1.40 +/- 0.05 was found to hold true between minor-loop remanence and hysteresis loss in the wide temperature range of 10 - 300 K, irrespective of particle size and cooling field. A coefficient deduced from the scaling law steeply increases with decreasing temperature and exhibits a cooling field dependence below T similar to 150 K. The value obtained after field cooling at 5 T was lower than that after zero-field cooling, being opposite to a behavior of major-loop coercivity. These observations were explained from the viewpoint of the exchange coupling between ferromagnetic Co core and antiferro-magnetic CoO shell, which becomes effective below T similar to 150 K. (C) 2017 Author(s).