Large grain-boundary magnetoresistance in MnFe2O4 nanoparticle compact

The low-field magnetoresistance (MR) has been investigated on the ferrite MnFe2O4 nanoparticle compact. At 300 K, a relatively large MR of 6% has been observed in an applied field of 5 kOe. With temperature decreasing, the MR ratio increases to a maximum of 12% at 100 K. These large MR are likely attributed to the spin-polarized tunneling of conducting electrons through the grain boundaries. The rapid drop of MR below 100 K reveals that there is a spin glass transition in this kind of compound.