Insights into the atomic structure of the interface of ferroelectric Hf0.5Zr0.5O2 grown epitaxially on La2/3Sr1/3MnO3
Insights into the atomic structure of the interface of ferroelectric Hf0.5Zr0.5O2 grown epitaxially on La2/3Sr1/3MnO3
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DOI：
10.1103/physrevmaterials.5.074410
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发表时间：
2021-07-28
影响因子：
3.4
通讯作者：
Gazquez, Jaume
中科院分区：
文献类型：
--
作者：
Estandia, Saul;Cao, Tengfei;Gazquez, Jaume
Hf0.5Zr0.5O2（HZO）薄膜的外延生长允许稳定的亚稳正交相具有强大的铁电性能。到目前为止，铁电相是最常见的钙钛矿衬底上插入缓冲层的La 2/3Sr 1/3 MnO 3（LSMO）的稳定;然而，鲜为人知的LSMO缓冲层和HZO和LSMO之间的界面所发挥的作用。通过扫描透射电子显微镜成像和电子能量损失谱检查HZO/LSMO/SrTiO 3异质结构表明，尽管HZO和LSMO之间存在大量结构失配，但它们之间的界面相对尖锐，跨越类似于2个原子层。的LSMO表面，预计主要是二氧化锰终止，经历了化学重建组成的Mn阳离子的Hf/Zr阳离子的混合物的替代。密度泛函理论计算表明，由Hf的MnO 2-终止的表面上的LSMO的Mn的取代是积极有利的，作为较高的电负性和价Hf相对于Mn平衡的MnO 2层的表面电荷。
Epitaxial growth of Hf0.5Zr0.5O2 (HZO) thin films allows for the stabilization of the metastable orthorhombic phase with robust ferroelectric properties. So far, the ferroelectric phase is most commonly stabilized on perovskite substrates upon insertion of a buffer layer of La2/3Sr1/3MnO3 (LSMO); however, little is known about the role played by the LSMO buffer layer and the interface between HZO and LSMO. Inspection of a HZO/LSMO/SrTiO3 heterostructure by scanning transmission electron microscope imaging and electron energy loss spectroscopy shows that, despite the substantial structural mismatch between HZO and LSMO, the interface between them is relatively sharp spanning similar to 2 atomic layers. The LSMO surface, expected to be mostly MnO2 terminated, undergoes a chemical reconstruction consisting of the substitution of the Mn cations by a mixture of Hf/Zr cations. Density functional theory calculations show that the substitution of Mn by Hf on the MnO2-terminated surface of LSMO is energetically favorable, as the higher electronegativity and valence of Hf with respect to Mn balances the surface charge of the MnO2 layer.