Magnetic phases of electron-doped manganites - art. no. 064431

We study the anisotropic magnetic structures exhibited by electron-doped ma nganites using a model which incorporates the double exchange between orbit ally degenerate e(g) electrons and the superexchange between t(2g) electron s with realistic values of the Hund's coupling (J(H)) the superexchange cou pling (J(AF)) and the bandwidth (W). We look at the relative stabilities of the G-, C-, and A-type antiferromagnetic phases. In particular we find tha t the G phase is stable for low electron doping as seen in experiments. We find good agreement with the experimentally observed magnetic phase diagram s of electron-doped manganites (x>0.5) such as Nd1-xSrxMnO3, Pr1-xSrxMnO3, and Sm1-xCaxMnO3. We can also explain the experimentally observed orbital s tructures of the C and A phases. We also extend our calculation for electro n-doped bilayer manganites of the form R(2-2x)A(1+2x)Mn(2)O(7) and predict that the C phase will be absent in these systems due to their reduced dimen sionality.