Size effects on EB in NiO NPs

Scrutinizing the role of size reduction on the exchange bias and dynamic magnetic behavior in NiO nanoparticles.
N Rinaldi-Montes, P Gorria, D Martínez-Blanco, A B Fuertes, L Fernández Barquín, I Puente-Orench and J A Blanco
Nanotechnology 26, 305705 (2015)

(a)–(d) Magnetic hysteresis loops for samples D2, D4 and D9 measured at selected temperatures, (a) 2, (b) 20, (c) 140 and (d) 300 K (that corresponding to a bulk NiO standard is included for the sake of comparison). (e)–(h) Enlarged views of the central part of the loops, evidencing the decrease in H_C and M_r with increasing temperature. The pictures inside (a)–(d) indicate the blocked/frozen (blue) or unblocked/unfrozen (red) regimes for the cores and shells, and correspond to samples D2 (top), D4 (middle) and D9 (bottom)