1. Jahn-Teller distortion in manganites

2. = Mn
= La, Pr
oxygen
La3+Mn3+O32-

3. = Mn
= La, Pr
oxygen
La3+Mn3+O32-

4. MnO6 octahedron

5. 25Mn: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d5
Mn3+: 1s2, 2s2, 2p6, 3s2, 3p6
, 3d4

6. 2p
Different Mn d-orbitals have diferrent overlaps with the oxygen p-orbital.

7. Mn3+ Eexch (Hund’s rule) 3 t2g 2 eg Ecrys 10 5
Different Mn d-orbitals have diferrent overlaps with the oxygen p-orbital. 10 5

8. Jahn-Teller distortion
The total energy is minimized by distorting the cubic unit cell. The degeneracy of the eg levels is removed by the crystal field of the distorted unit cell. The single eg electron can then be at a lower energy compared to the cubic unit cell. Hence the Mn3+ ion induces a Jahn-Teller distortion in the crystal. An Mn4+ ion will not induce J-T distortion because there is no eg electron. 5
Eexch
Mn3+
3 t2g
2 eg
Ecrys
EJT 10