![]() The non-saturation of magnetization up to 50 KOe applied magnetic field is due to its AFM core and surface disordered spins. In addition, the onset temperature for the EB effect in both NiO and NPs seems to follow a universal dependence with the NiO crystallite size. In nanoparticles, exchange bias like behaviour is due to the coreshell interaction of NPs and reported extensively for AFM nanoparticles 5, 28, 29, 43, 6972. The memory effect is responsible for spin glass behavior in the shell and exchange bias is due to core-shell interactions. Temperature-dependent magnetization of core-shell particles at high fields shows a deviation between field-cooled and zero-field-cooled curves below 30 K, suggesting the presence of frozen spins at the interface. In all the studied NPs, the variation of the EB field as a function of temperature is described according to a negative exponential law with a similar decay constant, yielding a vanishing EB effect around T similar to 40-50 K. CoCr 2 O 4 of 50 nm particles having core-shell structure demonstrate two different phenomena such as memory effect and exchange bias depending on temperature. Although exchange bias is a well-known effect of the exchange coupling between AFM and FM bilayers and core/shell nanoparticles 3337, hard-soft bilayers (. In contrast, the EB detected in NiO NPs is explained in a picture where uncompensated spins located on a magnetically disordered surface shell are exchange coupled to the antiferromagnetic core. The EB effect in NPs is attributed to the exchange coupling between the core and the shell, with an interfacial exchange energy of Delta E similar to 0.06 erg cm(-2), thus comparable to previous reports on Ni/NiO interfaces both in thin film and NP morphologies. With the aim of bridging the two systems, the diameter of the NiO NPs (similar to 4 nm) is chosen to be comparable to the shell thickness of ones (similar to 2 nm). The shell thickness dependence of the exchange bias of Fe/Fe 3 O 4 core-shell nanoparticles Date Added to IEEE Xplore: 16 July 2015 ISBN Information. The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for. In addition, the effect of shell thickness on the exchange bias blocking temperature and coercivity in Co-CoO core-shell nanoparticles has been studied by Thomas et al. In this framework, the role played by the magnetism of NiO at the nanoscale is investigated by comparing the microstructure and magnetic properties of NiO and NPs. An asymmetric shift of exchange bias loop in Ni Ni(OH) 2 core-shell nanoparticles has been observed by Maity and Roy. Bridging exchange bias effect in NiO and nanoparticles.Īmong all hi-magnetic core(transition metal oxide) nanoparticles (NPs), ones show an onset temperature for the exchange bias (EB) effect far below the Neel temperature of bulk antiferromagnetic NiO. Square core/shell nanoparticles with ferromagnetic core and antiferromagnetic shell were found to show an exchange bias, depending on the temperature, similar to spherical core/shell nanoparticles. ![]()
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