Please wait a minute...
Chin. Phys. B, 2026, Vol. 35(6): 067103    DOI: 10.1088/1674-1056/ae0b45
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES Prev   Next  

Moiré superlattice on the surface of Sm films driven by surface valence transition

Jianzhou Bian(边建州)1,†, Hao Zheng(郑浩)2,†, Yonghao Liu(刘永昊)3, Zongxiu Wu(邬宗秀)3, Yuan Zheng(郑远)3, Yi Yin(尹艺)3,‡, Yang Liu(刘洋)2,§, and Xiaofeng Xu(许晓峰)1,¶
1 School of Physics, Zhejiang University of Technology, Hangzhou 310023, China;
2 Center for Correlated Matter and School of Physics, Zhejiang University, Hangzhou 310058, China;
3 Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou 310027, China
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.
Keywords:  samarium      mixed valence      angle-resolved photoelectron spectroscopy      scanning tunneling microscopy  
Received:  27 May 2025      Revised:  25 August 2025      Accepted manuscript online:  25 September 2025
PACS:  71.27.+a (Strongly correlated electron systems; heavy fermions)  
  79.60.-i (Photoemission and photoelectron spectra)  
  68.37.Ef (Scanning tunneling microscopy (including chemistry induced with STM))  
  73.20.At (Surface states, band structure, electron density of states)  
Fund: Project supported by the National Key Research and Development Program of China (Grant Nos. 2022YFA1403202 and 2022YFA1402200), the National Natural Science Foundation of China (Grant Nos. 12174331 and 12274369), and the Zhejiang Provincial Natural Science Foundation of China (Grant No. LZ25A040003).
Corresponding Authors:  Yi Yin, Yang Liu, Xiaofeng Xu     E-mail:  yiyin@zju.edu.cn;yangliuphys@zju.edu.cn;xuxiaofeng@zjut.edu.cn

Cite this article: 

Jianzhou Bian(边建州), Hao Zheng(郑浩), Yonghao Liu(刘永昊), Zongxiu Wu(邬宗秀), Yuan Zheng(郑远), Yi Yin(尹艺), Yang Liu(刘洋), and Xiaofeng Xu(许晓峰) Moiré superlattice on the surface of Sm films driven by surface valence transition 2026 Chin. Phys. B 35 067103

[1] Coleman P 2007 Heavy Fermions: Electrons at the Edge of Magnetism, Handbook of Magnetism and Advanced Magnetic Materials, eds. Kronmuller H and Parkin S, Vol. 1: Fundamentals and Theory (Chichester: Wiley) pp. 1–54
[2] Gegenwart P, Si Q and Steglich F 2008 Nat. Phys. 4 186
[3] Kirchner S, Paschen S, Chen Q, Wirth S, Feng D, Thompson J D and Si Q 2020 Rev. Mod. Phys. 92 011002
[4] Varma C M 1976 Rev. Mod. Phys. 48 219
[5] Lawrence J M, Riseborough P S and Parks R D 1981 Rep. Prog. Phys. 44 1
[6] Riseborough P S and Lawrence J M 2016 Rep. Prog. Phys. 79 084501
[7] Chen Q Y, Xu D F, Niu X H, Jiang J, Peng R, Xu H C, Wen C H P, Ding Z F, Huang K, Shu L, Zhang Y J, Lee H, Strocov V N, Shi M, Bisti F, Schmitt T, Huang Y B, Dudin P, Lai X C, Kirchner S, Yuan H Q and Feng D L 2017 Phys. Rev. B 96 045107
[8] Yuan Y H, Duan Y X, Rusz J, Zhang C, Song J J, Wu Q Y, Sassa Y, Tjernverg O, Mansson M, Berntsen M H, Wu F Y, Liu S Y, Liu H, Zhu S X, Liu Z T, Zhao Y Z, Tobash P H, Bauer E D, Thompson J D, Oppeneer P M, Durakiewicz T and Meng J Q 2021 Phys. Rev. B 103 125122
[9] Strange P, Svane A, Temmerman W, Szotek Z and Winter H 1999 Nature 399 756
[10] Higashinaka R, Yamada A, Matsuda T D and Aoki Y 2018 AIP Advances 8 125017
[11] Wertheim G K and Crecelius G 1978 Phys. Rev. Lett. 40 813
[12] Allen J W, Johansson L I, Lindau I and Hagstrom S B 1980 Phys. Rev. B 21 1335
[13] Rosengren A and Johansson B 1982 Phys. Rev. B 26 3068
[14] Stenborg A, Andersen J N, Bjorneholm O, Nilsson A and M artensson N 1989 Phys. Rev. Lett. 63 187
[15] Lundgren E, Andersen J N, Nyholm R, Torrelles X, Rius J, Delin A, Grechnev A, Eriksson O, Konvicka C, Schmid M and Varga P 2002 Phys. Rev. Lett. 88 136102
[16] He F, Zhou Y, Ye Z, Cho S, Jeong J, Meng X and Wang Y 2021 ACS Nano 15 5944
[17] Lau C N, Bockrath M W, Mak K F and Zhang F 2022 Nature 602 41
[18] Mak K F and Shan J 2022 Nat. Nanotechnol. 17 686
[19] Nuckolls K P and Yazdani A 2024 Nat. Rev. Mater. 9 460
[20] Cao Y, Fatemi V, Fang S, Watanabe K, Taniguchi T, Kaxiras E and Jarillo-Herrero P 2018 Nature 556 43
[21] Park H, Cai J, Anderson E, Zhang Y, Zhu J, Liu X, Wang C, Holtzmann W, Hu C, Liu Z, Taniguchi T, Watanabe K, Chu J, Cao T, Fu L, Yao W, Chang C, Cobden D, Xiao D and Xu X 2023 Nature 622 74
[22] Xu F, Sun Z, Jia T, Liu C, Xu C, Li C, Gu Y, Watanabe K, Taniguchi T, Tong B, Jia J, Shi Z, Jiang S, Zhang Y, Liu X and Li T 2023 Phys. Rev. X 13 031037
[23] Kresse G and Hafner J 1993 Phys. Rev. B 47 558
[24] Perdew J P, Burke K and Ernzerhof M 1996 Phys. Rev. Lett. 77 3865
[25] Kresse G and Joubert D 1999 Phys. Rev. B 59 1758
[26] Denlinger J D, Allen J W, Kang J S, Sun K, Min B I, Kim D J and Fisk Z 2014 JPS Conf. Proc. 3 017038
[27] Chikina A, Generalov A, Kummer K, Guttler M, Antonov V N, Kucherenko Y, Kliemt K, Krellner C, Danzenbacher S, Kim T, Dudin P, Geibel C, Laubschat C and Vyalikh D V 2017 Phys. Rev. B 95 155127
[28] Yamaoka H, Thunstrom P, Jarrige I, Shimada K, Tsujii N, Arita M, Iwasawa H, Hayashi H, Jiang J, Habuchi T, Hirayama D, Namatame H, Taniguchi M, Murao U, Hosoya S, Tamaki A and Kitazawa H 2012 Phys. Rev. B 85 115120
[29] Zheng H, Xiao Z, Pan Z, Yang G, Liu Y, Bian J, Wu Y, Hua T, Zhang J, Lu J, Li J, Sun T, Song Y, He R, Larrea Jimenez J, Cao G, Yuan H, Xu Y, Yin Y, Shi M, Cao C and Liu Y 2025 Sci. China- Phys. Mech. Astron. 68 287511
[30] Wang P, Ni J F, Li H N, Zhang W H and Zhu J F 2008 Surf. Sci. 602 3728
[31] Kaindl G, Hohr A, Weschke E, Vandr e S, Schußler-Langeheine C and Laubschat C 1995 Phys. Rev. B 51 7920
[32] Tarasov A V, Glazkova D, Schulz S, Poelchen G, Kliemt K, Kraiker A, Muntwiler M, Laubschat C, Generalov A, Polley C, Krellner C, Vyalikh D V and Usachov D Y 2022 Phys. Rev. B 106 155136
[33] Dzero M, Sun K, Galitski V and Coleman P 2010 Phys. Rev. Lett. 104 106408
[34] Li L, Sun K, Kurdak C and Allen J W 2020 Nat. Rev. Phys. 2 463
[35] Jiang J, Li S, Zhang T, Sun Z, Chen F, Ye Z R, Xu M, Ge Q Q, Tan S Y, Niu X H, Xia M, Xie B P, Li Y F, Chen X H, Wen H H and Feng D L 2013 Nat. Commun. 4 3010
[36] Chatterjee S, Ruf J P, Wei H I, Finkelstein K D, Schlom D G and Shen K M 2017 Nat. Commun. 8 852
[37] Lisi S, Lu X, Benschop T, de Jong T A, Stepanov P, Duran J R, Margot F, Cucchi I, Cappelli E, Hunter A, Tamai A, Kandyba V, Giampietri A, Barinov A, Jobst J, Stalman V, Leeuwenhoek M, Watanabe K, Taniguchi T, Rademaker L, van der Molen S J, Allan M P, Efetov D K and Baumberger F 2021 Nat. Phys. 17 189
[38] Chen C, Nuckolls K P, Ding S, Miao W, Wong D, Oh M, Lee R L, He S, Peng C, Pei D, Li Y, Hao C, Yan H, Xiao H, Gao H, Li Q, Zhang S, Liu J, He L, Watanabe K, Taniguchi T, Jozwiak C, Bostwick A, Rotenberg E, Li C, Han X, Pan D, Liu Z, Dai X, Liu C, Bernevig B A, Wang Y, Yazdani A and Chen Y 2024 Nature 636 342
[1] Spectroscopic studies of two-dimensional superconductivity
Qiang-Jun Cheng(程强军), Xu-Cun Ma(马旭村), Qi-Kun Xue(薛其坤), and Can-Li Song(宋灿立). Chin. Phys. B, 2026, 35(6): 066801.
[2] Real-space imaging of kagome flat band localization in Fe3Sn2
Yifan Wang(汪逸凡), Lili Jiang(蒋利利), Qiang Zhang(张强), Zhiyong Lin(林志勇), Hui Zhang(张汇), and Changgan Zeng(曾长淦). Chin. Phys. B, 2026, 35(3): 036801.
[3] Characterization of antisite defects and in-gap states in antiferromagnetic MnSb2Te4
Junming Zhang(张峻铭), Ming Xi(席明), Yuchong Zhang(张羽翀), Hang Li(李航), Jiali Zhao(赵佳丽), Hechang Lei(雷和畅), Zhongxu Wei(魏忠旭), and Tian Qian(钱天). Chin. Phys. B, 2025, 34(7): 076801.
[4] Surface solitonic charge distribution on 2D materials investigated using Kelvin probe force microscopy technique based on qplus atomic force microscopy
Rui Song(宋睿), Feng Hao(郝峰), Jie Yang(杨杰), Lifeng Yin(殷立峰), and Jian Shen(沈健). Chin. Phys. B, 2025, 34(5): 056802.
[5] Epitaxial growth of Bi nanowires on Pb-√77 × √3 surface
Siyu Huo(霍思宇), Jieying Li(李洁莹), Yuzhou Liu(刘宇舟), Desheng Cai(蔡德胜), Yitong Gu(谷易通), Haoen Chi(迟浩恩), Wenhui Pang(庞文慧), Gan Yu(于淦), Xiaoying Shi(史晓影), Wenguang Zhu(朱文光), and Shengyong Qin(秦胜勇). Chin. Phys. B, 2025, 34(10): 106801.
[6] Surface evolution of thermoelectric material KCu4Se3 explored by scanning tunneling microscopy
Yumin Xia(夏玉敏), Ni Ma(马妮), Desheng Cai(蔡德胜), Yuzhou Liu(刘宇舟), Yitong Gu(谷易通), Gan Yu(于淦), Siyu Huo(霍思宇), Wenhui Pang(庞文慧), Chong Xiao(肖翀), and Shengyong Qin(秦胜勇). Chin. Phys. B, 2024, 33(8): 086804.
[7] Superconducting state in Ba(1-x)SrxNi2As2 near the quantum critical point
Chengfeng Yu(余承峰), Zongyuan Zhang(张宗源), Linxing Song(宋林兴), Yanwei Wu(吴彦玮), Xiaoqiu Yuan(袁小秋), Jie Hou(侯杰), Yubing Tu(涂玉兵), Xingyuan Hou(侯兴元), Shiliang Li(李世亮), and Lei Shan(单磊). Chin. Phys. B, 2024, 33(6): 066802.
[8] Bimodal growth of Fe islands on graphene
Yi-Sheng Gu(顾翊晟), Qiao-Yan Yu(俞俏滟), Dang Liu(刘荡), Ji-Ce Sun(孙蓟策), Rui-Jun Xi(席瑞骏), Xing-Sen Chen(陈星森), Sha-Sha Xue(薛莎莎), Yi Zhang(章毅), Xian Du(杜宪), Xu-Hui Ning(宁旭辉), Hao Yang(杨浩), Dan-Dan Guan(管丹丹), Xiao-Xue Liu(刘晓雪), Liang Liu(刘亮), Yao-Yi Li(李耀义), Shi-Yong Wang(王世勇), Can-Hua Liu(刘灿华), Hao Zheng(郑浩), and Jin-Feng Jia(贾金锋). Chin. Phys. B, 2024, 33(6): 068104.
[9] Field induced Chern insulating states in twisted monolayer-bilayer graphene
Zhengwen Wang(王政文), Yingzhuo Han(韩英卓), Kenji Watanabe, Takashi Taniguchi, Yuhang Jiang(姜宇航), and Jinhai Mao(毛金海). Chin. Phys. B, 2024, 33(6): 067301.
[10] Revisit of the anisotropic vortex states of 2H-NbSe2 towards the zero-field limit
Fan Zhang(张凡), Xingyuan Hou(侯兴元), Yuxuan Jiang(姜宇轩), Zongyuan Zhang(张宗源), Yubing Tu(涂玉兵), Xiangde Zhu(朱相德), Genfu Chen(陈根富), and Lei Shan(单磊). Chin. Phys. B, 2024, 33(6): 067401.
[11] Microscopic growth mechanism and edge states of monolayer 1T'-MoTe2
Haipeng Zhao(赵海鹏), Yin Liu(刘隐), Shengguo Yang(杨胜国), Chenfang Lin(林陈昉), Mingxing Chen(陈明星), Kai Braun, Xinyi Luo(罗心仪), Siyu Li(李思宇), Anlian Pan(潘安练), and Xiao Wang(王笑). Chin. Phys. B, 2024, 33(4): 046801.
[12] Growth and characterization of Bi(110)/CrTe2 heterostructures: Exploring interplay between magnetism and topology
Zhenyu Yuan(袁震宇), Fazhi Yang(杨发枝), Baiqing Lv(吕佰晴), Yaobo Huang(黄耀波), Tian Qian(钱天), Jinpeng Xu(徐金朋), and Hong Ding(丁洪). Chin. Phys. B, 2024, 33(2): 026802.
[13] Distinct behavior of electronic structure under uniaxial strain in BaFe2As2
Jiajun Li(李佳俊), Giao Ngoc Phan, Xingyu Wang(王兴玉), Fazhi Yang(杨发枝), Quanxin Hu(胡全欣), Ke Jia(贾可), Jin Zhao(赵金), Wenyao Liu(刘文尧), Renjie Zhang(张任杰), Youguo Shi(石友国), Shiliang Li(李世亮), Tian Qian(钱天), and Hong Ding(丁洪). Chin. Phys. B, 2024, 33(1): 017401.
[14] Manipulating charge density wave state in kagome compound RbV3Sb5
Yu-Xin Meng(孟雨欣), Cheng-Long Xue(薛成龙), Li-Guo Dou(窦立国), Wei-Min Zhao(赵伟民), Qi-Wei Wang(汪琪玮), Yong-Jie Xu(徐永杰), Xiangqi Liu(刘祥麒), Wei Xia(夏威), Yanfeng Guo(郭艳峰), and Shao-Chun Li(李绍春). Chin. Phys. B, 2023, 32(9): 096801.
[15] Effects of atomic corrugations on electronic structures in Pb1-xBix thin films
Pengju Li(李鹏举), Kun Xie(谢鹍), Yumin Xia(夏玉敏), Desheng Cai(蔡德胜), and Shengyong Qin(秦胜勇). Chin. Phys. B, 2023, 32(6): 066101.
No Suggested Reading articles found!