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中国物理学会期刊

铜/锰异质结中维度驱动的交换耦合效应

Dimensionality driven exchange coupling effect in cuprate-manganite superlattices

CSTR: 32037.14.aps.73.20240849
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  • 过渡金属氧化物异质结界面处各种自由度之间的耦合与竞争关系, 极大地丰富了其物理性质, 并拓展了相关应用范围. 已有研究报道指出维度是调控氧化物异质结性能的有效手段. 本文采用脉冲激光沉积技术制备出高质量外延生长的 SrCuO2/La0.7Ca0.3MnO3 (SCO/LCMO)超晶格, 通过控制维度实现了对超晶格中交换耦合效应的有效调控. 实验发现, 在改变 SCO 厚度的过程中, 其结构将由无限层状构型转变为链状构型, 进而导致异质结界面处氧配位环境的改变. X 射线吸收谱测试证实超晶格中存在电荷转移现象. 在 SCO 较薄时, Mn-O-Cu 之间超交换作用产生的弱磁矩将钉扎铁磁 LCMO 层. 随着 SCO 厚度的增加, 异质结界面处电荷转移减小. 与此同时, SCO 层具有的反铁磁序与邻近铁磁层 LCMO 作用, 导致了交换偏置的产生. 本实验证实了维度在氧化物异质结多功能调控中的重要作用.

     

    The coupling and competition between various degrees of freedom at the interface of transition metal oxide heterointerfaces greatly enrich their physical properties and expand their relevant application scope. It has been reported that dimensionality is an effective method to regulate the properties of oxide heterostructure. The structure of SCO film exhibits a planar-type-to-chain-type transformation with the change of thickness. In this work, the high-quality SCO/LCMO superlattices are deposited by a pulsed laser deposition system. And the interfacial exchange coupling effect is effectively manipulated by controlling the dimensionality of SCO layer. X-ray absorption spectrum (XAS) measurement shows that the charge transfer occurs at the heterointerface. When the SCO layer is thin, the interfacial superexchange coupling supported by charge transfer generates a weak magnetic moment to pin the ferromagnetic LCMO layer. As the SCO layer thickens, the charge transfer will decrease. Meanwhile, the long-range antiferromagnetic order in thicken SCO layer can interact with LCMO layer, resulting in the exchange bias effect. This experiment confirms the important role of dimensionality in modulating the properties in multifunctional oxide heterostructure.

     

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