Lu Xiangle, Liu Jishan, Zhang Nian, Xie Binping, Yang Shuai, Liu Wanling, Jiang Zhicheng, Huang Zhe, Yang Yichen, Miao Jin, Li Wei, Cho Soohyun, Liu Zhengtai, Liu Zhonghao, Shen Dawei
State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.
Adv Sci (Weinh). 2022 Jul;9(21):e2105864. doi: 10.1002/advs.202105864. Epub 2022 May 23.
Fundamental understanding and control of the electronic structure evolution in rare-earth nickelates is a fascinating and meaningful issue, as well as being helpful to understand the mechanism of recently discovered superconductivity. Here the dimensionality effect on the ground electronic state in high-quality (NdNiO ) /(SrTiO ) superlattices is systematically studied through transport and soft X-ray absorption spectroscopy. The metal-to-insulator transition temperature decreases with the thickness of the NdNiO slab decreasing from bulk to 7 unit cells, then increases gradually as m further reduces to 1 unit cell. Spectral evidence demonstrates that the stabilization of insulating phase can be attributed to the increase of the charge-transfer energy between O 2p and Ni 3d bands. The prominent multiplet feature on the Ni L edge develops with the decrease of NdNiO slab thickness, suggesting the strengthening of the charge disproportionate state under the dimensional confinement. This work provides convincing evidence that dimensionality is an effective knob to modulate the charge-transfer energy and thus the collective ground state in nickelates.
对稀土镍酸盐中电子结构演变的基本理解和控制是一个引人入胜且有意义的问题，同时也有助于理解最近发现的超导机制。在此，通过输运和软X射线吸收光谱系统地研究了高质量（NdNiO）/（SrTiO）超晶格中维度对基态电子态的影响。金属-绝缘体转变温度随着NdNiO平板厚度从体相减小到7个晶胞而降低，然后随着厚度进一步减小到1个晶胞而逐渐升高。光谱证据表明，绝缘相的稳定可归因于O 2p和Ni 3d能带之间电荷转移能的增加。随着NdNiO平板厚度的减小，Ni L边显著的多重态特征逐渐显现，这表明在维度限制下电荷非均匀态得到加强。这项工作提供了令人信服的证据，即维度是调节电荷转移能从而调控镍酸盐中集体基态的有效手段。
