Anomalous narrow-band correlation in a natural superconducting heterostructure
- 1Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- 2Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Türkiye
Abstract
A new frontier in condensed matter physics is to stack atomically thin layered materials with different properties and create intriguing phenomena which do not exist in any of the constituent layers. Transition metal dichalcogenide 4Hb-TaS2, with an alternating stacking of a spin liquid candidate 1T-TaS2 and a superconductor 1H-TaS2, is a natural heterostructure for such a purpose. Recently, rare phenomena were indeed observed, including chiral superconductivity, two-component nematic superconductivity, topological surface superconductivity, and enigmatic magnetic memory. A widely proposed starting point to understand such a mysterious heterostructure requires strong electronic correlation, presumably provided by 1T-TaS2 layers with a narrow flat band near the Fermi level (EF). Here, by using angle-resolved photoemission spectroscopy, we reveal the theoretically expected flat band near EF in the energy-momentum space. However, this flat band only exists on the 1T-TaS2 terminated surface layer with broken translational symmetry, but not on the 1T-TaS2 subsurface layers buried in the bulk. These results directly challenge the foundation of the current theoretical paradigm. On the 1T-TaS2 terminated surface layer, we further revealed a pseudogap and an anomalous doping effect. These phenomena and the dichotomy between surface and bulk layers also shed light on the unusual coexistence of distinct electronic orders in this mysterious heterostructure.
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BibTeX
@article{sun2026anomalous,
title = {{Anomalous narrow-band correlation in a natural superconducting heterostructure}},
author = {Xiupeng Sun and Zhiyuan Wei and Min Shan and Shuting Peng and Zhuying Wang and Ping Wu and Yang Luo and Jianchang Shen and Linwei Huai and Yu Miao and Zhipeng Ou and Mehmet Onbasli and Zhenyu Wang and Tao Wu and Junfeng He and Xianhui Chen},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
year = {2026},
month = oct,
doi = {10.1073/pnas.2609173123},
url = {https://doi.org/10.1073/pnas.2609173123},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Anomalous narrow-band correlation in a natural superconducting heterostructure
AU - Xiupeng Sun
AU - Zhiyuan Wei
AU - Min Shan
AU - Shuting Peng
AU - Zhuying Wang
AU - Ping Wu
AU - Yang Luo
AU - Jianchang Shen
AU - Linwei Huai
AU - Yu Miao
AU - Zhipeng Ou
AU - Mehmet Onbasli
AU - Zhenyu Wang
AU - Tao Wu
AU - Junfeng He
AU - Xianhui Chen
PY - 2026
DA - 2026/10/21
JO - Proceedings of the National Academy of Sciences of the United States of America
DO - 10.1073/pnas.2609173123
UR - https://doi.org/10.1073/pnas.2609173123
AB - A new frontier in condensed matter physics is to stack atomically thin layered materials with different properties and create intriguing phenomena which do not exist in any of the constituent layers. Transition metal dichalcogenide 4Hb-TaS2, with an alternating stacking of a spin liquid candidate 1T-TaS2 and a superconductor 1H-TaS2, is a natural heterostructure for such a purpose. Recently, rare phenomena were indeed observed, including chiral superconductivity, two-component nematic superconductivity, topological surface superconductivity, and enigmatic magnetic memory. A widely proposed starting point to understand such a mysterious heterostructure requires strong electronic correlation, presumably provided by 1T-TaS2 layers with a narrow flat band near the Fermi level (EF). Here, by using angle-resolved photoemission spectroscopy, we reveal the theoretically expected flat band near EF in the energy-momentum space. However, this flat band only exists on the 1T-TaS2 terminated surface layer with broken translational symmetry, but not on the 1T-TaS2 subsurface layers buried in the bulk. These results directly challenge the foundation of the current theoretical paradigm. On the 1T-TaS2 terminated surface layer, we further revealed a pseudogap and an anomalous doping effect. These phenomena and the dichotomy between surface and bulk layers also shed light on the unusual coexistence of distinct electronic orders in this mysterious heterostructure.
SN - 0027-8424
SN - 1091-6490
ER -