Particle-size effects on the value of Tc of MnFe2O4 : Evidence for finite-size scaling

Abstract

57Fe Mössbauer measurements show that the Tc of 〈12〉-nm particles of MnFe2O4 is higher than that of the 〈33〉-nm particles, which exhibit the bulk Tc value (573 K). The 57Fe isomer shift as well as the internal field are, however, independent of the particle size, as is the cation distribution determined by Mn and Fe extended x-ray absorption fine structure and Mn x-ray absorption near-edge structure measurements at different temperatures. The results confirm that the higher Tc of the 〈12〉-nm particles arises from finite-size scaling.