Study of disorder in pulsed laser deposited double perovskite oxides by first-principle structure prediction
Study of disorder in pulsed laser deposited double perovskite oxides by first-principle structure prediction
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DOI：
10.1038/s41524-021-00561-1
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发表时间：
2021-06
影响因子：
9.7
通讯作者：
E. Fertitta;Sujit Das;D. Banerjee;F. Ebrahimi;C. Barraud;K. Du;He Tian;C. Pickard;C. Weber;R. Ramesh;P. Littlewood;David Dubbink
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作者：
E. Fertitta;Sujit Das;D. Banerjee;F. Ebrahimi;C. Barraud;K. Du;He Tian;C. Pickard;C. Weber;R. Ramesh;P. Littlewood;David Dubbink
双钙钛矿氧化物，具有通式A_2BBO_6，由于其多铁性和电荷转移特性而引起广泛的兴趣。它们提供了广泛的潜在应用，如自旋电子学和电可调器件。然而，遇到了很大的实际限制，因为B位阳离子的自发有序是众所周知的难以实现的。在这项联合实验和理论工作中，我们专注于双钙钛矿La2TiFeO6和La2VCuO6薄膜的脉冲激光沉积和观察到的B位无序和B位离子之间的部分电荷转移的解释的表征。采用随机结构抽样方法，研究了多相竞争的结构熵。为了在现实的实验条件下捕获最相关的竞争微观状态的代表性图片，该搜索还包括非化学计量相的潜在形成，这也可能与观察到的部分电荷转移直接相关。我们优化的信息封装在势能景观，通过结构采样捕获，通过评估的熵和熵项。这些术语被用作不同阶段竞争的度量。这种方法，在本文中具体应用于La2TiFeO6，突出了基态以上的高熵相的存在，这可以解释在更广泛的双钙钛矿氧化物中经常观察到的无序。
Double perovskite oxides, with generalized formula A2BBO6, attract wide interest due to their multiferroic and charge transfer properties. They offer a wide range of potential applications such as spintronics and electrically tunable devices. However, great practical limitations are encountered, since a spontaneous order of the B-site cations is notoriously hard to achieve. In this joint experimental-theoretical work, we focused on the characterization of double perovskites La2TiFeO6and La2VCuO6films grown by pulsed laser deposition and interpretation of the observed B-site disorder and partial charge transfer between the B-site ions. A random structure sampling method was used to show that several phases compete due to their corresponding configurational entropy. In order to capture a representative picture of the most relevant competing microstates in realistic experimental conditions, this search included the potential formation of non-stoichiometric phases as well, which could also be directly related to the observed partial charge transfer. We optimized the information encapsulated in the potential energy landscape, captured via structure sampling, by evaluating both enthalpic and entropic terms. These terms were employed as a metric for the competition of different phases. This approach, applied herein specifically to La2TiFeO6, highlights the presence of highly entropic phases above the ground state which can explain the disorder observed frequently in the broader class of double perovskite oxides.