Surface d-orbital order in an intermetallic compound

Orbital order describes a quantum state where occupied orbitals line up in a periodic pattern. Although orbital physics plays a fundamental and universal role in strongly correlated electron systems, the existence and particularly the band-structure fingerprint of orbital order remain a long-standing mystery. Here we report the discovery of rare earth 5d-orbital order developed by the surface states of the intermetallic compound Tb2CoAl4Ge2. Angle-resolved photoemission spectroscopy reveals characteristic nematic features such as Fermi surface deformation and band splitting. These experimental observations can be described by a ferro-orbital order term in the mean-field Hamiltonian. The structural and magnetic origin of such order is excluded by systematic high-resolution neutron powder diffraction and scanning tunnelling microscopy measurements. Our results provide strong evidence for a pure surface orbital order scenario avoiding complications from structural distortion as in colossal magnetoresistance manganites, magnetic order as in iron-based superconductors and charge transfer p-orbital order in cuprates. Whether orbital order can exist with a clear band-structure fingerprint in correlated materials has remained unresolved. Now an orbital order from rare earth 5d electrons without structural or magnetic order is seen in an intermetallic compound.

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Publication Details

Journal
Nature Physics
Published
2026-06-29
DOI
https://doi.org/10.1038/s41567-026-03359-4
Primary Topic
Iron-based superconductors research
Type
article
Field-Weighted Citation Impact
0.00

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article

Surface d-orbital order in an intermetallic compound

Massimo Tallarida, Kenichi Ozawa, Zhengtai Liu, Weidong Zhao et al.
Nature Physics
Iron-based superconductors research
article

Surface d-orbital order in an intermetallic compound

Massimo Tallarida, Kenichi Ozawa, Zhengtai Liu, Weidong Zhao, Zuowei Liang, Jiaou Wang, C B Liu, Zijuan Xie, Wanru Ma, J. Dai, Ping Miao, Wanlin Cheng, Junze Deng, Kai Chen, Haohao Sheng, K. Shimada, Xianhui Chen, Junhao Lin, Wen-Gen Zheng, Zhanyang Hao, Shengtao Cui, Jiandong Guo, Jia‐Wei Mei, Zhenyu Wang, Zhijun Wang, Liusuo Wu, Mao Ye, Shuki Torii, Xuetao Zhu, Yongqing Cai, Wu Xie, Y D Xie, Kazuhiro MORI, Zhibin Su, Yogendra Kumar
article en

Abstract

Orbital order describes a quantum state where occupied orbitals line up in a periodic pattern. Although orbital physics plays a fundamental and universal role in strongly correlated electron systems, the existence and particularly the band-structure fingerprint of orbital order remain a long-standing mystery. Here we report the discovery of rare earth 5d-orbital order developed by the surface states of the intermetallic compound Tb2CoAl4Ge2. Angle-resolved photoemission spectroscopy reveals characteristic nematic features such as Fermi surface deformation and band splitting. These experimental observations can be described by a ferro-orbital order term in the mean-field Hamiltonian. The structural and magnetic origin of such order is excluded by systematic high-resolution neutron powder diffraction and scanning tunnelling microscopy measurements. Our results provide strong evidence for a pure surface orbital order scenario avoiding complications from structural distortion as in colossal magnetoresistance manganites, magnetic order as in iron-based superconductors and charge transfer p-orbital order in cuprates. Whether orbital order can exist with a clear band-structure fingerprint in correlated materials has remained unresolved. Now an orbital order from rare earth 5d electrons without structural or magnetic order is seen in an intermetallic compound.

Nature Physics
Hiroshima University (JP), University of Science and Technology of China (CN), High Energy Accelerator Research Organization (JP), Chinese Academy of Sciences (CN), Dalian University of Technology (CN), Dongguan University of Technology (CN), ALBA Synchrotron (Spain) (ES), Southern University of Science and Technology (CN), China Spallation Neutron Source (CN), Shanghai Advanced Research Institute (CN), Songshan Lake Materials Laboratory (CN), Institute of High Energy Physics (CN), National Synchrotron Radiation Laboratory (CN), Institute of Physics (CN), National Laboratory for Superconductivity (CN), University of Chinese Academy of Sciences (CN)
Salt Science Research Foundation, National Natural Science Foundation of China, National Natural Science Foundation of China-Yunnan Joint Fund, Basic and Applied Basic Research Foundation of Guangdong Province
Openalex Percentile: Top 19%
Iron-based superconductors research
DOIOpen Access PDFOpenAlex
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