Ideal superspin glass behaviour in a random-close-packed ensemble of maghemite nanoparticles

8th International Conference on Fine Particle Magnetism

De Toro, J.A.^1 ; Lee, S.S.^2 ; Mathieu, R.^3 ; Normile, P.S.^1 ; Salazar, D.^1 ; Cheong, J.L.^2 ; Muñiz, P.^1 ; Riveiro, J.M.^1 ; Hillenkamp, M.^4 ; Tamion, A.^4 ; Tournus, F.^4 ; Nordblad, P.^3

Instituto Regional de Investigación Cientifica Aplicada (IRICA), Departamento de Fisica Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain^1

Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore^2

Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala, Sweden^3

Institut Lumière Matière, UMR5306, University Lyon 1-CNRS, 69622 Villeurbanne, France^4

关键词: Ac susceptibility;    Critical exponent;    Field dependence;    Freezing transition;    Maghemite nanoparticle;    Normalized temperature;    Spherical particle;    Zero-field cooled magnetization;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/521/1/012011/pdf
DOI  :  10.1088/1742-6596/521/1/012011

来源: IOP

【 摘 要 】

Highly uniform (8 nm) bare maghemite nanoparticles were pressed into a disc with a volume fraction close to the characteristic filling factor of random-close-packed ensembles of spherical particles. We review the ideal superspin glass behaviour exhibited by this material, including an onset of the absorption component of the ac susceptibility at the freezing transition as sharp (in a normalized temperature scale) as those observed in atomic spin glasses, narrow memory dips in the zero-field cooled magnetization, and a spin-glass characteristic field-dependence of the susceptibility. Critical exponents were extracted from static and dynamic scaling analysis.