First-principles study of metastable charge ordering states in La_1/3Sr_2/3FeO₃

L_1/3Sr_2/3FeO₃ exhibits the metal-to-insulator transition accompanying both antiferromagnetic and charge ordering states with the Fe-O bond disproportionation below T=200K.

Here, we study possible metastable states of charge ordering structures in this material using the first-principle and climbing nudged elastic band methods (CINEB).

In the strong correlation regime, L_1/3Sr_2/3FeO₃  is an antiferromagnetic insulator with a charge ordering state, consistent with the experimental measurement of this material at the low temperature. As the correlation becomes weak, we find two possible metastable charge ordering states with distinct Fe-O bond disproportionations.The electronic structure of these metastable charge ordering states are noticeably different from that of the ground-state. We compute the energy landscape across different metastable states and find the energy barrier is as small as $\sim$10meV, which can be easily accessed by the optical measurements.

Our results can provide an insightful explanation to multiple metastable charge ordering states and the slow dynamics of this and related oxide materials.