Structure, magnetism and colossal magnetoresistance behavior in A2Mn2O7 pyrochlores (A = Dy-Lu, Y, Sc, in or Tl)

This paper presents a bird's eye view of the structural, electrical and magnetic properties of A2Mn2O7 (A = rare earth, Y, Sc, In, T)) phases crystallizing in pyrochlore-related structure. Electrical measurements indicate the compounds containing rare earth, Y, Sc or In are insulators whereas Tl2Mn2O7 is highly conducting. All the compounds show spontaneous magnetization at low temperatures indicating ferromagnetic transitions. Detailed ac and …