Oxide superlattices reveal a rich array of emergent properties derived from the composition modulation and the resulting lattice distortion, charge transfer, and symmetry reduction that occur at the interfaces between the layers. The great majority of studies have focused on perovskite oxide superlattices, revealing, for example, the appearance of an interfacial 2D electron gas, magnetic moment, or improper ferroelectric polarization that is not present in the parent phases. Garnets possess greater structural complexity than perovskites: the cubic garnet unit cell contains 160 atoms with the cations distributed between three different coordination sites, and garnets exhibit a wide range of useful properties, including ferrimagnetism and ion transport. However, there have been few reports of the synthesis or properties of garnet superlattices, with layer thicknesses approaching the unit cell dimension of 1.2 nm. Here, we describe superlattices made from Bi and rare earth (RE = Tm, Tb, Eu, Lu) iron garnets (IGs) grown by pulsed laser deposition. Atom probe tomography and transmission electron microscopy reveal the composition modulation without dislocations and layer thicknesses as low as 0.45 nm, less than half a unit cell. TmIG/TbIG superlattices exhibit perpendicular magnetic anisotropy that is qualitatively different from the in-plane anisotropy of the solid solution, and BiIG/LuIG superlattices exhibit ferromagnetic resonance linewidth characteristics of the end-members rather than the solid solution. Garnet superlattices provide a playground for exploring interface physics within the vast parameter space of cation coordination and substitution.

中文翻译：

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具有亚基单元组成调制的稀土铁石榴石超晶格


氧化物超晶格揭示了一系列丰富的涌现特性，这些特性来自成分调制以及由此产生的晶格失真、电荷转移和对称性降低，这些特性发生在层之间的界面处。绝大多数研究都集中在钙钛矿氧化物超晶格上，例如，揭示了界面二维电子气、磁矩或母相中不存在的不当铁电极化的出现。柘榴石比钙钛矿具有更大的结构复杂性：立方柘榴石晶胞包含 160 个原子，阳离子分布在三个不同的配位位点之间，柘榴石表现出广泛的有用特性，包括亚铁磁性和离子传输。然而，关于石榴石超晶格的合成或性质的报道很少，层厚度接近 1.2 nm 的晶胞尺寸。在这里，我们描述了由脉冲激光沉积生长的 Bi 和稀土 （RE = Tm， Tb， Eu， Lu） 铁石榴石 （IG） 制成的超晶格。原子探针断层扫描和透射电子显微镜揭示了无位错的成分调制，层厚低至 0.45 nm，小于半个晶胞。TmIG/TbIG 超晶格表现出与固溶体的面内各向异性在质上不同的垂直磁各向异性，而 BiIG/LuIG 超晶格表现出端元而不是固溶体的铁磁共振线宽特性。石榴石超晶格为在阳离子配位和取代的广阔参数空间中探索界面物理学提供了一个游乐场。