近日，日本鸠山日立株式会社研发组的Toshiaki Tanigaki及其研究团队取得一项新进展。经过不懈努力，他们实现单个铁磁晶格面的电子全息观察。相关研究成果已于2024年7月3日在国际权威学术期刊《自然》上发表。

本文报道了在无磁场条件下，采用数字后像差校正辅助的硬件型像差校正器，并结合电子全息术，成功揭示了具有非均匀结构的材料内部单一晶格平面上（如铁磁性双钙钛矿氧化物Ba₂FeMoO₆中的(111)晶格面）由Fe³⁺与Mo⁵⁺离子相反自旋排列所产生的净磁矩磁相。这一突破性发现为直接观测众多材料及器件中局部区域（诸如界面与晶界）的磁晶格结构开辟了新的途径。

据悉，在探索新的基础材料和器件时，对特定局部区域的原子尺度观测将非常有益。电子显微镜中硬件型像差校正的发展使原子分辨率的局部结构观测以及化学和振动分析成为可能。然而，在磁成像中，通过将样品置于强磁场中，通过电子能量损失谱分析原子级自旋构型，这破坏了样品中磁序性质。虽然无磁场观测可以通过晶胞平均可视化反铁磁体的固有磁场，但直接观察非均匀结构的单个原子层的磁场是具有挑战性的。

附：英文原文

Title: Electron holography observation of individual ferrimagnetic lattice planes

Author: Tanigaki, Toshiaki, Akashi, Tetsuya, Yoshida, Takaho, Harada, Ken, Ishizuka, Kazuo, Ichimura, Masahiko, Mitsuishi, Kazutaka, Tomioka, Yasuhide, Yu, Xiuzhen, Shindo, Daisuke, Tokura, Yoshinori, Murakami, Yasukazu, Shinada, Hiroyuki

Issue&Volume: 2024-07-03

Abstract: Atomic-scale observations of a specific local area would be considerably beneficial when exploring new fundamental materials and devices. The development of hardware-type aberration correction in electron microscopy has enabled local structural observations with atomic resolution as well as chemical and vibration analysis. In magnetic imaging, however, atomic-level spin configurations are analysed by electron energy-loss spectroscopy by placing samples in strong magnetic fields, which destroy the nature of the magnetic ordering in the samples. Although magnetic-field-free observations can visualize the intrinsic magnetic fields of an antiferromagnet by unit-cell averaging, directly observing the magnetic field of an individual atomic layer of a non-uniform structure is challenging. Here we report that the magnetic fields of an individual lattice plane inside materials with a non-uniform structure can be observed under magnetic-field-free conditions by electron holography with a hardware-type aberration corrector assisted by post-digital aberration correction. The magnetic phases of the net magnetic moments of (111) lattice planes formed by opposite spin orderings between Fe³⁺ and Mo⁵⁺ in a ferrimagnetic double-perovskite oxide (Ba₂FeMoO₆) were successfully observed. This result opens the door to direct observations of the magnetic lattice in local areas, such as interfaces and grain boundaries, in many materials and devices.

DOI: 10.1038/s41586-024-07673-w

Source: https://www.nature.com/articles/s41586-024-07673-w