La_(0.67)Sr_(0.33)MnO_(3)薄膜相图的轨道弹性调控

Orbital elasticity control of phase diagram for La_(0.67)Sr_(0.33)MnO_(3) films

过渡金属氧化物具有丰富的功能性,但其错综复杂的内部自由度对相图绘制和结构设计提出了挑战.本文中,我们引入了描述相图物理起源的轨道能级序(ELO),并通过对La_(0.67)Sr_(0.33)MnO_(3)(LSMO)氧化物的研究证明了其在相图预测中的有效性.结合DFT计算和实验,我们构建了氧含量和应变关联的LSMO相图,结果表明LSMO结构稳定性与ELO密切相关.据此发现了一种由ELO演化而产生的四倍氧有序相.最后,我们提出了描述轨道分裂程度的轨道弹性定律,阐明了ELO演化的起源,助力功能氧化物的设计.这项研究拓宽了材料科学领域的性能调控手段,并为从轨道角度预测相图提供了思路.

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_(0.67)Sr_(0.33)MnO_(3)(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.