Surface reconstruction modulated superconductivity on quasi-2D iron pnictide superconductor KCa2Fe4As4F2

doi:10.1088/1674-1056/add5cb

中国物理B ›› 2025, Vol. 34 ›› Issue (8): 87402-087402.doi: 10.1088/1674-1056/add5cb

Surface reconstruction modulated superconductivity on quasi-2D iron pnictide superconductor KCa₂Fe₄As₄F₂

Wenjing Zeng(曾文静)¹, Zongyuan Zhang(张宗源)^1,2,†, Xiaoyan Dong(董晓燕)¹, Yubing Tu(涂玉兵)^1,2, Yanwei Wu(吴彦玮)¹, Teng Wang(王腾)³, Fan Zhang(张凡)⁵, Shuai Shao(邵帅)¹, Jie Hou(侯杰)^1,2, Xingyuan Hou(侯兴元)^1,2, Ning Hao(郝宁)⁴, Gang Mu(牟刚)^3,‡, and Lei Shan(单磊)^1,2,§

1 Information Materials and Intelligent Sensing Laboratory of Anhui Province, Leibniz International Joint Research Center of Materials Sciences of Anhui Province, Anhui University, Hefei 230601, China;
2 Center of Free Electron Laser and High Magnetic Field, Institutes of Physical Science and Information Technology, Hefei 230601, China;
3 State Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China;
4 Anhui Provincial Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
5 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

收稿日期:2025-03-20 修回日期:2025-04-23 接受日期:2025-05-08 出版日期:2025-07-17 发布日期:2025-08-05
通讯作者: Zongyuan Zhang, Gang Mu, Lei Shan E-mail:zongyuanzhang@ahu.edu.cn;mugang@mail.sim.ac.cn;lshan@ahu.edu.cn
基金资助:
Project supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA1611103 and 2022YFA1403203), the Innovation Program for Quantum Science and Technology (Grant Nos. 2024ZD0301300 and 2021ZD0302802), and the National Natural Science Foundation of China (Grant Nos. 12474128, 12374133, 12204008, and 12104004).

Surface reconstruction modulated superconductivity on quasi-2D iron pnictide superconductor KCa₂Fe₄As₄F₂

1 Information Materials and Intelligent Sensing Laboratory of Anhui Province, Leibniz International Joint Research Center of Materials Sciences of Anhui Province, Anhui University, Hefei 230601, China;
2 Center of Free Electron Laser and High Magnetic Field, Institutes of Physical Science and Information Technology, Hefei 230601, China;
3 State Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China;
4 Anhui Provincial Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
5 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

Received:2025-03-20 Revised:2025-04-23 Accepted:2025-05-08 Online:2025-07-17 Published:2025-08-05
Contact: Zongyuan Zhang, Gang Mu, Lei Shan E-mail:zongyuanzhang@ahu.edu.cn;mugang@mail.sim.ac.cn;lshan@ahu.edu.cn
Supported by:
Project supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA1611103 and 2022YFA1403203), the Innovation Program for Quantum Science and Technology (Grant Nos. 2024ZD0301300 and 2021ZD0302802), and the National Natural Science Foundation of China (Grant Nos. 12474128, 12374133, 12204008, and 12104004).

摘要/Abstract

摘要： Iron-based superconductors (FeSCs) feature a complex phase diagram, and their diverse cleavage terminations offer a versatile platform for modulating surface electronic states and investigating the underlying superconducting mechanisms. In this study, we explore the surface modulation of KCa$_{2}$Fe$_{4}$As$_{4}$F$_{2}$ using scanning tunneling microscopy/spectroscopy. Cryogenically cleaved surfaces reveal multiple configurations, including $\sqrt 2 \times \sqrt 2$ reconstruction, $1 \times 2$ and $1 \times 3$ stripes, as well as nanoscale vacancies. Reducing potassium coverage induces hole doping, which shifts the density of states peak toward the Fermi level and suppresses the superconducting gap from 4.8 meV to 3.2 meV. This behavior is reminiscent of the Van Hove singularity observed in hole-doped 122-type FeSCs. The band structure does not undergo a simple rigid shift, and the evolution of superconductivity can be attributed to the interplay between surface carriers and electronic correlations. Additionally, a V-shaped gap is observed at a unique location preserving the FeAs bilayer structure, where interlayer coupling effects are likely involved. The diversity of surface structures and electronic states in K12442 enhances our understanding of FeSCs and facilitates the modulation and application of FeAs superconducting layers.

关键词: iron-based superconductor, surface reconstruction, carrier doping, van Hove singularity, electronic correlation

Abstract: Iron-based superconductors (FeSCs) feature a complex phase diagram, and their diverse cleavage terminations offer a versatile platform for modulating surface electronic states and investigating the underlying superconducting mechanisms. In this study, we explore the surface modulation of KCa$_{2}$Fe$_{4}$As$_{4}$F$_{2}$ using scanning tunneling microscopy/spectroscopy. Cryogenically cleaved surfaces reveal multiple configurations, including $\sqrt 2 \times \sqrt 2$ reconstruction, $1 \times 2$ and $1 \times 3$ stripes, as well as nanoscale vacancies. Reducing potassium coverage induces hole doping, which shifts the density of states peak toward the Fermi level and suppresses the superconducting gap from 4.8 meV to 3.2 meV. This behavior is reminiscent of the Van Hove singularity observed in hole-doped 122-type FeSCs. The band structure does not undergo a simple rigid shift, and the evolution of superconductivity can be attributed to the interplay between surface carriers and electronic correlations. Additionally, a V-shaped gap is observed at a unique location preserving the FeAs bilayer structure, where interlayer coupling effects are likely involved. The diversity of surface structures and electronic states in K12442 enhances our understanding of FeSCs and facilitates the modulation and application of FeAs superconducting layers.

Key words: iron-based superconductor, surface reconstruction, carrier doping, van Hove singularity, electronic correlation

中图分类号: (Tunneling phenomena: single particle tunneling and STM)

74.55.+v

73.25.+i (Surface conductivity and carrier phenomena) 74.25.-q (Properties of superconductors) 07.79.Cz (Scanning tunneling microscopes)

Wenjing Zeng(曾文静), Zongyuan Zhang(张宗源), Xiaoyan Dong(董晓燕), Yubing Tu(涂玉兵), Yanwei Wu(吴彦玮), Teng Wang(王腾), Fan Zhang(张凡), Shuai Shao(邵帅), Jie Hou(侯杰), Xingyuan Hou(侯兴元), Ning Hao(郝宁), Gang Mu(牟刚), and Lei Shan(单磊). Surface reconstruction modulated superconductivity on quasi-2D iron pnictide superconductor KCa₂Fe₄As₄F₂[J]. 中国物理B, 2025, 34(8): 87402-087402.

参考文献

[1] Paglione J and Greene R L 2010 Nat. Phys. 6 645
[2] Fernandes R M, Coldea A I, Ding H, Fisher I R, Hirschfeld P J and Kotliar G 2022 Nature 601 35
[3] Yi M, Zhang Y, Shen Z X and Lu D H 2017 Npj Quantum Mater. 2 57
[4] Kordyuk A A 2012 Low Temp. Phys. 38 888
[5] Ishida S, Song D, Ogino H, Iyo A and Eisaki H 2017 Phys. Rev. B 95 014517
[6] Canfield P C and Bud’ko S L 2010 Ann. Rev. Condens. Matter Phys. 1 27
[7] Yamazaki T, Takeshita N, Kobayashi R, Fukazawa H, Kohori Y, Kihou K, Lee C H, Kito H, Iyo A and Eisaki H 2010 Phys. Rev. B 81 224514
[8] Alireza P L, Ko Y T C, Gillett J, Petrone C M, Cole J M, Lonzarich G G and Sebastian S E 2009 J. Phys.: Condens. Matter 21 012208
[9] Wen C H P, Xu H C, Chen C, Huang Z C, Lou X, Pu Y J, Song Q, Xie B P, Abdel Hafiez M, Chareev D A, Vasiliev A N, Peng R and Feng D L 2016 Nat. Commun. 7 6433
[10] Niu X H, Chen S D, Jiang J, Ye Z R, Yu T L, Xu D F, Xu M, Feng Y, Yan Y J, Xie B P, Zhao J, Gu D C, Sun L L, Mao Q, Wang H, Fang M, Zhang C J, Hu J P, Sun Z and Feng D L 2016 Phys. Rev. B 93 054516
[11] Wang Q Y, Li Z, ZhangWH, Zhang Z C, Zhang J S, LiW, Ding H, Ou Y B, Deng P, Chang K, Wen J, Song C L, He K, Jia J F, Ji S H, Wang Y Y, Wang L L, Chen X, Ma X C and Xue Q K 2012 Chin. Phys. Lett. 29 037402
[12] Song C L, Zhang H M, Zhong Y, Hu X P, Ji S H, Wang L L, He K, Ma X C and Xue Q K 2016 Phys. Rev. Lett. 116 157001
[13] Zhang C, Hu T, Wang T, Wu Y, Yu A, Chu J, Zhang H, Zhang X, Xiao H, Peng W, Di Z, Qiao S and Mu G 2021 2D Mater. 8 025024
[14] Chang K, Deng P, Zhang T, Lin H C, Zhao K, Ji S H, Wang L L, He K, Ma X C, Chen X and Xue Q K 2015 Europhys. Lett. 109 28003
[15] Ueda S, Yamagishi T, Takeda S, Agatsuma S, Takano S, Mitsuda A and Naito M 2011 Physica C 471 1167
[16] Li M, Li G, Cao L, Zhou X T, Wang X C, Jin C Q, Chiu C K, Pennycook S J, Wang Z Q and Gao H J 2022 Nature 606 890
[17] Nag P K, Scott K, De Carvalho V S, Byland J K, Yang X Z,Walker M, Greenberg A G, Klavins P, Miranda E, Gozar A, Taufour V, Fernandes R M and Da Silva Neto E H 2024 Nat. Phys. 21 89
[18] Gao M, Ma F J, Lu Z Y and Xiang T 2010 Phys. Rev. B 81 193409
[19] Liu W Y, Cao L, Zhu S Y, Kong L Y, Wang G W, Papaj M, Zhang P, Liu Y B, Chen H, Li G, Yang F Z, Kondo T, Du S X, Cao G H, Shin S, Fu L, Yin Z P, Gao H J and Ding H 2020 Nat. Commun. 11 5866
[20] Shao S, Zhang F, Zhang Z Y, Wang T, Wu Y W, Tu Y B, Hou J, Hou X Y, Hao N, Mu G and Shan L 2023 Sci. China-Phys. Mech. Astron. 66 287412
[21] Duan W, Chen K L, Hong W S, Chen X Y, Yang H, Li S L, Luo H Q and Wen H H 2021 Phys. Rev. B 103 214518
[22] Stolyarov V S, Pervakov K S, Astrakhantseva A S, Golovchanskiy I A, Vyalikh D V, Kim T K, Eremeev S V, Vlasenko V A, Pudalov V M, Golubov A A, Chulkov E V and Roditchev D 2020 J. Phys. Chem. Lett. 11 9393
[23] Koepernik K, Johnston S, Heumen V, Huang Y, Kaas J, Goedkoop J B, Golden M S and Brink J V D 2012 Phys. Rev. Lett. 109 127001
[24] Li A, Yin J X, Wang J H, Wu Z, Ma J H, Sefat A S, Sales B C, Mandrus D G, McGuire M A, Jin R Y, Zhang C L, Dai P C, Lv B, Chu C W, Liang X J, Hor P H, Ting C S and Pan S H 2019 Phys. Rev. B 99 134520
[25] Yin J X, Wu X X, Li J, Wu Z, Wang J H, Ting C S, Hor P H, Liang X J, Zhang C L, Dai P C, Wang X C, Jin C Q, Chen G F, Hu J P, Wang Z Q, Li A, Ding H and Pan S H 2020 Phys. Rev. B 102 054515
[26] Hu Q X, Yang F Z, Wang X Y, Li J J, Liu W Y, Kong L Y, Li S L, Yan L, Xu J P and Ding H 2023 Phys. Rev. Mater. 7 034801
[27] Zhang H, Dai J, Zhang Y J, Qu D R, Ji H W, Wu G, Wang X F, Chen X H, Wang B, Zeng C G, Yang J L and Hou J G 2010 Phys. Rev. B 81 104520
[28] Wu D S, Hong W S, Dong C X, et al. 2020 Phys. Rev. B 101 224508
[29] Pyon S, Kobayashi Y, Takahashi A, LiWJ,Wang T, Mu G, Ichinose A, Kambara T, Yoshida A and Tamegai T 2020 Phys. Rev. Mater. 4 104801
[30] Wang Z C, He C, Wu S Q, Tang Z T, Liu Y, Ablimit A, Feng C M and Cao G H 2016 J. Am. Chem. Soc. 138 7856
[31] Chen X Y, Duan W, Fan X W, Hong W S, Chen K L, Yang H, Li S L, Luo H Q and Wen H H 2021 Phys. Rev. Lett. 126 257002
[32] Hou Z Y, Chen K L, HongWS,Wang D, DuanW, Yang H, Li S L, Luo H Q, Wang Q H, Xiang T and Wen H H 2025 Phys. Rev. X 15 011027
[33] Hong WS, Song L X, Liu B, Li Z Z, Zeng Z Y, Li Y, Wu D S, Sui Q T, Xie T, Danilkin S, Ghosh H, Ghosh A, Hu J P, Zhao L, Zhou X J, Qiu X G, Li S L and Luo H Q 2020 Phys. Rev. Lett. 125 117002
[34] Wang Z C, Liu Y, Wu S Q, Shao Y T, Ren Z and Cao G H 2019 Phys. Rev. B 99 144501
[35] Fang D L, Shi X, Du Z Y, Richard P, Yang H, Wu X X, Zhang P, Qian T, Ding X X, Wang Z Y, Kim T K, Hoesch M, Wang A F, Chen X H, Hu J P, Ding H and Wen H H 2015 Phys. Rev. B 92 144513
[36] Wang T, Chu J N, Jin H, Feng J X, Wang L L, Song Y K, Zhang C, Xu X G, Li W, Li Z J, Hu T, Jiang D, Peng W, Liu X S and Mu G 2019 J. Phys. Chem. C 123 13925
[37] Duan W, Chen K L, Hong W S, Chen X Y, Li S L, Luo H Q, Yang H and Wen H H 2022 Nano Lett. 22 9450
[38] Li P, Liao S,Wang Z C, Li H X, Su SW, Zhang J K, Chen Z Y, Jiang Z C, Liu Z T, Yang L X, Huai L W, He J F, Cui S T, Sun Z, Yan Y J, Cao G H, Shen D W, Jiang J and Feng D L 2024 Nat. Commun. 15 6433
[39] Liu X, Tao R, Ren M Q, Chen W, Yao Q, Wolf T, Yan Y J, Zhang T and Feng D L 2019 Nat. Commun. 10 1039
[40] De’Medici L, Giovannetti G and Capone M 2014 Phys. Rev. Lett. 112 177001
[41] Li J, Zhao D, Wu Y P, Li S J, Song D W, Zheng L X, Wang N Z, Luo X G, Sun Z, Wu T and Chen X H 2016 arxiv.org/abs/1611.04694
[42] Li G, Liang L, Li Q, Pan M, Nascimento V B, He X, Karki A B, Meunier V, Jin R, Zhang J and Plummer E W 2014 Phys. Rev. Lett 112 077205

Surface reconstruction modulated superconductivity on quasi-2D iron pnictide superconductor KCa₂Fe₄As₄F₂

Surface reconstruction modulated superconductivity on quasi-2D iron pnictide superconductor KCa₂Fe₄As₄F₂

RichHTML

PDF (PC)

赞

可视化

摘要/Abstract

引用本文

使用本文

参考文献

相关文章 15

Metrics

本文评价

推荐阅读 0

[1]	Yuxin Ma(马宇欣), Munan Hao(郝木难), Qi Li(李琦), Ke Ma(马克), Haodong Li(李浩东), Duo Zhang(张铎), Ruijin Sun(孙瑞锦), Shifeng Jin(金士锋), and Changchun Zhao(赵长春). Dimensional crossover from quasi-2D to 3D superconductivity in (Li,Fe)OHFeSe_1-xS_x driven by chemical pressure[J]. 中国物理B, 2025, 34(6): 67402-067402.
[2]	Xianghe Han(韩相和), Zhongyi Cao(曹钟一), Zihao Huang(黄子豪), Zhen Zhao(赵振), Haitao Yang(杨海涛), Hui Chen(陈辉), and Hong-Jun Gao(高鸿钧). Emergent 3×3 charge order on the Cs reconstruction of kagome superconductor CsV₃Sb₅[J]. 中国物理B, 2025, 34(1): 16801-016801.
[3]	Man Li(李满), Huan Ma(马欢), Rui Lou(娄睿), and Shancai Wang(王善才). Electronic band structures of topological kagome materials[J]. 中国物理B, 2025, 34(1): 17101-017101.
[4]	Meng Lyu(吕孟), Yang Liu(刘洋), Shen Zhang(张伸), Junyan Liu(刘俊艳), Jinying Yang(杨金颖), Yibo Wang(王一博), Yiting Feng(冯乙婷), Xuebin Dong(董学斌), Binbin Wang(王彬彬), Hongxiang Wei(魏红祥), and Enke Liu(刘恩克). Anomalous Hall effect and electronic correlation in a spin-reoriented kagome antiferromagnet LuFe₆Sn₆[J]. 中国物理B, 2024, 33(10): 107507-107507.
[5]	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). Distinct behavior of electronic structure under uniaxial strain in BaFe₂As₂[J]. 中国物理B, 2024, 33(1): 17401-17401.
[6]	Hong-Chao Yang(杨洪超), Peng-Cheng Liu(刘鹏程), Liu-Yu Mu(穆鎏羽), Ying-De Li(李英德), Kai Han(韩锴), and Xiao-Le Qiu(邱潇乐). Multiferroic monolayers VOX (X = Cl, Br, I): Tunable ferromagnetism via charge doping and ferroelastic switching[J]. 中国物理B, 2023, 32(6): 67701-067701.
[7]	Dongdong Ding(丁冬冬), Ruirui Niu(牛锐锐), Xiangyan Han(韩香岩), Zhuangzhuang Qu(曲壮壮), Zhiyu Wang(王知雨), Zhuoxian Li(李卓贤), Qianling Liu(刘倩伶), Chunrui Han(韩春蕊), and Jianming Lu(路建明). Tunable correlation in twisted monolayer-trilayer graphene[J]. 中国物理B, 2023, 32(6): 67204-067204.
[8]	Hongsheng Liu(柳洪盛), Yuanyuan Zhao(赵圆圆), Shi Qiu(邱实), Jijun Zhao(赵纪军), and Junfeng Gao(高峻峰). Reconstruction and stability of Fe₃O₄(001) surface: An investigation based on particle swarm optimization and machine learning[J]. 中国物理B, 2023, 32(5): 56802-056802.
[9]	Delong Fang(方德龙) and Yunkang Cui(崔云康). Discrete vortex bound states with a van Hove singularity in the vicinity of the Fermi level[J]. 中国物理B, 2023, 32(5): 57401-057401.
[10]	Di Liu(刘迪), Xingyu Wang(王兴玉), Zezhong Li(李泽众), Xiaoyan Ma(马肖燕), and Shiliang Li(李世亮). Focused-ion-beam assisted technique for achieving high pressure by uniaxial-pressure devices[J]. 中国物理B, 2023, 32(4): 47401-047401.
[11]	Xiangyan Han(韩香岩), Qianling Liu(刘倩伶), Ruirui Niu(牛锐锐), Zhuangzhuang Qu(曲壮壮), Zhiyu Wang(王知雨), Zhuoxian Li(李卓贤), Chunrui Han(韩春蕊), Kenji Watanabe, Takashi Taniguchi, Zizhao Gan(甘子钊), and Jianming Lu(路建明). Spontaneous isospin polarization and quantum Hall ferromagnetism in a rhombohedral trilayer graphene superlattice[J]. 中国物理B, 2023, 32(11): 117201-117201.
[12]	Ruirui Niu(牛锐锐), Xiangyan Han(韩香岩), Zhuangzhuang Qu(曲壮壮), Zhiyu Wang(王知雨), Zhuoxian Li(李卓贤), Qianling Liu(刘倩伶), Chunrui Han(韩春蕊), and Jianming Lu(路建明). Correlated states in alternating twisted bilayer-monolayer-monolayer graphene heterostructure[J]. 中国物理B, 2023, 32(1): 17202-017202.
[13]	Ruizhi Qiu(邱睿智), Liuhua Xie(谢刘桦), and Li Huang(黄理). Site selective 5f electronic correlations in β-uranium[J]. 中国物理B, 2023, 32(1): 17101-017101.
[14]	Qiang-Tao Sui(随强涛) and Xiang-Gang Qui(邱祥冈). Josephson vortices and intrinsic Josephson junctions in the layered iron-based superconductor Ca₁₀(Pt₃As₈)((Fe_0.9Pt_0.1)₂As₂)₅[J]. 中国物理B, 2022, 31(9): 97403-097403.
[15]	Geng Li(李更), Shiyu Zhu(朱诗雨), Peng Fan(范朋), Lu Cao(曹路), and Hong-Jun Gao(高鸿钧). Exploring Majorana zero modes in iron-based superconductors[J]. 中国物理B, 2022, 31(8): 80301-080301.