Structural and magnetic properties of CoO-Pt core-shell nanoparticles

0431708 - FZÚ 2015 RIV US eng J - Journal Article
Zeleňáková, A. - Zeleňák, V. - Michalik, Štefan - Kováč, J. - Meisel, M. W.
Structural and magnetic properties of CoO-Pt core-shell nanoparticles.
Physical Review. B. Roč. 89, č. 10 (2014), "104417-1"-"104417-10". ISSN 1098-0121
Institutional support: RVO:68378271
Keywords : CoO-Pt core shell nanoparticles * superparamagnetism * superspin glass state * x-ray diffraction * x-ray absorption spectroscopy
Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders
Impact factor: 3.736, year: 2014

Using microemulsion methods, CoO-Pt core-shell nanoparticles were synthesized and characterized by transmission electron microscopy, x-ray diffraction and x-ray absorption spectroscopy, which confirmed the existence of CoO cores and pure Pt surface layers. Using a magnetometer, the ac and dc magnetic properties were investigated over a range of temperature (2 K ≤T≤ 300 K), magnetic field (≤50 kOe), and frequency (≤1 kHz). The data suggest the presence of two different magnetic regimes whose onsets are identified at 6 K and 37 K, respectively. The magnetic behavior around 37 K indicates a superparamagnetic blocking of interacting nanoparticle moments. The behavior at 6 K characterizes a collective freezing of the nanoparticle moments in a superspin glass state. This co-existence of blocking and freezing behaviors is consistent with the presence of an antiferromagnetically ordered core and a magnetically disordered interlayer between the CoO core and the Pt shell.
Permanent Link: http://hdl.handle.net/11104/0236294