Kim Jong-Woo, Choi Yongseong, Middey S, Meyers D, Chakhalian J, Shafer Padraic, Park H, Ryan Philip J
Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Phys Rev Lett. 2020 Mar 27;124(12):127601. doi: 10.1103/PhysRevLett.124.127601.
Correlated electrons give rise to both exotic electronic and magnetic properties in rare-earth nickelates. Here we present evidence of the interfacial coupling between two nickelate systems, EuNiO_{3} (ENO) and LaNiO_{3} (LNO), with different electronic and magnetic properties but with compatible structural registry giving rise to an electrostructural transition, unobserved in each constituent. Nominally, LNO remains in a paramagnetic-metallic R3[over ¯]c phase while orthorhombic ENO undergoes antiferromagnetic and insulating transitions. However, the ENO/LNO heterostructure displays a uniform rotational symmetry set by an entwined interface. This leads to an anomalous reduction of bond disproportionation in the ENO layer through the metal to insulator transition and concomitantly charge disproportionation opens the gap accompanied by antiferromagnetic ordering. Our results resolve a long-standing question in the physics of rare-earth nickelates, herein demonstrating that charge and bond disproportionation are competing mechanisms for the charge localization process in the rare-earth nickelate system.
关联电子在稀土镍酸盐中产生了奇异的电学和磁学性质。在此，我们展示了两种具有不同电学和磁学性质但具有兼容结构配准的镍酸盐体系，即EuNiO₃（ENO）和LaNiO₃（LNO）之间界面耦合的证据，这种耦合导致了一种在每个组分中均未观察到的电结构转变。名义上，LNO保持在顺磁金属R3[上划线]c相，而正交晶系的ENO经历反铁磁和绝缘转变。然而，ENO/LNO异质结构表现出由缠绕界面设定的均匀旋转对称性。这导致通过金属到绝缘体转变，ENO层中键的歧化异常减少，同时电荷歧化打开能隙并伴随着反铁磁有序化。我们的结果解决了稀土镍酸盐物理学中一个长期存在的问题，在此证明电荷和键的歧化是稀土镍酸盐体系中电荷局域化过程的竞争机制。
