近日，韩国基础科学研究院的Tae Won Noh及其研究小组与首尔大学的Se Young Park以及浦项科技大学的Daesu Lee等人合作并取得一项新进展。经过不懈努力，他们实现铁磁性金属的挠性电极化与控制。相关研究成果已于2024年1月17日在国际知名学术期刊《自然—物理学》上发表。
据悉，电极化在绝缘体中有明确的定义，但在金属中还没有通用的方案来诱导和控制整体极性。
该研究团队利用非均匀晶格应变产生的伪电场，即挠曲电场，作为极化和控制金属的手段，从而绕过了上述限制。通过异质外延和原子尺度成像技术，研究人员发现挠曲电场极化了中心对称的SrRuO3金属的主体，并使Ru离子偏离中心位移。这进一步影响了挠曲极性SrRuO3的电子带和晶格各向异性，可能导致电子相关性、铁磁性和各向异性的增强。除了传统的电场之外，挠曲电场还可以通过纯原子位移来产生和控制电子态。
附：英文原文
Title: Flexoelectric polarizing and control of a ferromagnetic metal
Author: Peng, Wei, Park, Se Young, Roh, Chang Jae, Mun, Junsik, Ju, Hwiin, Kim, Jinkwon, Ko, Eun Kyo, Liang, Zhengguo, Hahn, Sungsoo, Zhang, Jinfeng, Sanchez, Ana M., Walker, David, Hindmarsh, Steven, Si, Liang, Jo, Yong Jin, Jo, Yongjoo, Kim, Tae Heon, Kim, Changyoung, Wang, Lingfei, Kim, Miyoung, Lee, Jong Seok, Noh, Tae Won, Lee, Daesu
Issue&Volume: 2024-01-17
Abstract: Electric polarization is well defined only in insulators not metals, and there is no general scheme to induce and control bulk polarity in metals. Here we circumvent this limitation by utilizing a pseudo-electric field generated by inhomogeneous lattice strain, namely a flexoelectric field, as a means of polarizing and controlling a metal. Using heteroepitaxy and atomic-scale imaging, we show that flexoelectric fields polarize the bulk of an otherwise centrosymmetric metal SrRuO3, with off-centre displacements of Ru ions. This further impacts the electronic bands and lattice anisotropy of the flexo-polar SrRuO3, potentially leading to an enhancement of electron correlation, ferromagnetism and its anisotropy. Beyond conventional electric fields, flexoelectric fields may be used to create and control electronic states through pure atomic displacements.
DOI: 10.1038/s41567-023-02333-8
Source: https://www.nature.com/articles/s41567-023-02333-8