Orbital elasticity control of phase diagram for La_0.67Sr_0.33MnO₃ films

Transition metal oxides display rich functionalities, but intricate internal degrees of freedom pose a challenge to understanding phase diagrams as a road map for material exploration. Here, the order of orbital energy level (ELO) as a physical principle of phase diagrams is introduced and demonstrated to be effective by employing La_0.67Sr_0.33-MnO₃ (LSMO) oxides. A phase diagram of LSMO associated with the oxygen content and strain is built combining DFT calculations and experiments, in which the structural stability is closely related to ELO. We thereby find a new phase with four-fold oxygen ordering as a result of ELO evolution. More important, orbital elasticity law, describing the degree of orbital splitting, is proposed to clarify the origin of ELO evolution, with the objective of design of functional oxides with specific functionality. This work broadens the means of performance modulation in the field of materials science and opens up an opportunity for phase diagram prediction from an orbital perspective. (Figure presented.)