Nuclear57Fe relaxation in Fe2+-containing NiFe2O4 and CoFe2O4 single crystals

Spinel ferrite nanocrystals embedded inside ZnO: Magnetic, electronic, and magnetotransport properties

“…Note that both bulk NiFe 2 O 4 and CoFe 2 O 4 are insulators with resistivity of 10 2 -10 3 Ωcm at room temperature 2,9 . The resistivity of NiFe 2 O 4 single crystals monotonically increases with decreasing temperature 52 . However, the corresponding thin film materials can be rather conductive 2 .…”

“…At low temperatures the impurities freeze out. In Ref 52,. the authors show that in their measured temperature range from around 77 K to room temperature the NiFe 2 O 4 single crystals exhibit semiconducting conductivity, and the activation energy is around 60 meV.…”