Double perovskites (DP, A₂BB’O₆) exhibit a breadth of multifunctional properties with a huge potential range of applications, including magneto-optic and spintronic devices. However, spontaneous cation ordering is limited by the similar size and charge of B and B’ cations. We introduce a route to stimulate B-site rock-salt ordering. By growing thin films on (111)-oriented substrates, ‘in-plane’ strain acts on the intrinsically tilted oxygen octahedra of the DP and produces two different B-site cages (in size and shape), stimulating spontaneous cation ordering. For the ferromagnetic insulator La₂CoMnO₆, clear Co/Mn ordering was achieved by growing on (111)-oriented substrates. The difference in B-site cages was further enhanced when grown under minor (111) in-plane compressive strain, resulting in long-range ordering with a saturation magnetization of 5.8 μ_B/formula unit (f.u.), close to the theoretical 6 μ_B/f.u., without antiferromagnetic behavior. Our approach enables the study of many new ordered DPs which have never been made before.

双钙钛矿（DP，阿₂ BB” ø ₆）表现出多功能性的广度与一个巨大的潜在的应用范围，包括磁光和自旋电子器件。但是，自发阳离子的有序性受到B和B'阳离子相似的大小和电荷的限制。我们介绍了一种刺激B站点岩盐排序的途径。通过在（111）取向的衬底上生长薄膜，“面内”应变作用于DP的固有倾斜的氧八面体上，并产生两个不同的B位笼（尺寸和形状），从而刺激了自发的阳离子排列。对于铁磁绝缘子La ₂ CoMnO ₆通过在（111）取向的衬底上生长，可以实现清晰的Co / Mn有序化。在差分乙-site笼当次要下（111）生长的能力进一步增强的面内压应变，造成长程有序的5.8μ的饱和磁化_乙/式单元（FU），接近理论6μ _B / fu，无反铁磁行为。我们的方法可以研究许多以前从未有过的新订购的DP。