An orbital strategy for regulating the Jahn–Teller effect

The Jahn–Teller effect (JTE) arising from lattice–electron coupling is a fascinating phenomenon that profoundly affects important physical properties in a number of transition-metal compounds. Controlling JT distortions and their corresponding electronic structures is highly desirable to tailor the functionalities of materials. Here, we propose a local coordinate strategy to regulate the JTE through quantifying occupancy in the d_z2 and d_x2_−y2 orbitals of Mn and scrutinizing the symmetries of the ligand oxygen atoms in MnO₆ octahedra in LiMn₂O₄ and Li_0.5Mn₂O₄. The effectiveness of such a strategy has been demonstrated by constructing P2-type NaLi_xMn_1–xO₂ oxides with different Li/Mn ordering schemes. In addition, this strategy is also tenable for most 3dtransition-metal compounds in spinel and perovskite frameworks, indicating the universality of local coordinate strategy and the tunability of the lattice–orbital coupling in transition-metal oxides. This work demonstrates a useful strategy to regulate JT distortion and provides useful guidelines for future design of functional materials with specific physical properties.