Moiré superlattice on the surface of Sm films driven by surface valence transition
Year: 2025
Type: article
Abstract: Rare earth (RE) metals exhibit unique mixed-valence behavior due to their 4f electronic configurations. In this study, we investigate the surface electronic structure and valence-mixing phenomena in samarium (Sm) films using molecular beam epitaxy (MBE), scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT). A natural moiré superlattice emerges on the Sm film surface as a result of lattice mismatch between the surface divalent Sm 2+ and bulk trivalent Sm 3+ layers. ARPES reveals the flat f electron bands corresponding to Sm 3+ and Sm 2+ states, particularly demonstrating the partial coexistence of bulk Sm 2+ flat bands. The dispersive s–d electron bands and surface-condition-induced band shifts are observed and analyzed through both STM and ARPES measurements. Our work provides direct evidence for the formation of a moiré pattern on the surface of Sm films due to its unique surface valence transition, thus paving the way for a new method to generate moiré superlattices in correlated 4f-electron systems.
Source: Chinese Physics B
Authors: Jianzhou 建州 Bian 边, Hao 浩 Zheng 郑, Yonghao 永昊 Liu 刘, Zongxiu 宗秀 Wu 邬, Yuan 远 Zheng 郑, Yi 艺 Yin 尹, Yang 洋 Liu 刘, Xiaofeng 晓峰 Xu 许
Institutions: Zhejiang University of Technology, Zhejiang University
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,500
OpenAlex ID: W4414530526