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Li H, Wang G, Ding N, Ren Q, Zhao G, Lin W, Yang J, Yan W, Li Q, Yang R, Yuan S, Denlinger JD, Wang Z, Zhang X, Wray LA, Dong S, Qian D, Miao L. Spectroscopic evidence of spin-state excitation in d-electron correlated semiconductor FeSb 2. Proc Natl Acad Sci U S A 2024; 121:e2321193121. [PMID: 38954549 PMCID: PMC11252798 DOI: 10.1073/pnas.2321193121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 05/28/2024] [Indexed: 07/04/2024] Open
Abstract
Iron antimonide (FeSb2) has been investigated for decades due to its puzzling electronic properties. It undergoes the temperature-controlled transition from an insulator to an ill-defined metal, with a cross-over from diamagnetism to paramagnetism. Extensive efforts have been made to uncover the underlying mechanism, but a consensus has yet to be reached. While macroscopic transport and magnetic measurements can be explained by different theoretical proposals, the essential spectroscopic evidence required to distinguish the physical origin is missing. In this paper, through the use of X-ray absorption spectroscopy and atomic multiplet simulations, we have observed the mixed spin states of 3d 6 configuration in FeSb2. Furthermore, we reveal that the enhancement of the conductivity, whether induced by temperature or doping, is characterized by populating the high-spin state from the low-spin state. Our work constitutes vital spectroscopic evidence that the electrical/magnetical transition in FeSb2 is directly associated with the spin-state excitation.
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Affiliation(s)
- Huayao Li
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - Guohua Wang
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
| | - Ning Ding
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - Quan Ren
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - Gan Zhao
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - Wenting Lin
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - Jinchuan Yang
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
| | - Wensheng Yan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei230029, China
| | - Qian Li
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei230029, China
| | - Run Yang
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - Shijun Yuan
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | | | - Zhenxing Wang
- Wuhan National High Magnetic Field Center & School of Physics, Huazhong University of Science and Technology, Wuhan430074, China
| | - Xiaoqian Zhang
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - L. Andrew Wray
- Department of Physics, New York University, New York, NY10003
| | - Shuai Dong
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
| | - Dong Qian
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing210093, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai200240, China
| | - Lin Miao
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing211189, China
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Prediction of unconventional magnetism in doped FeSb 2. Proc Natl Acad Sci U S A 2021; 118:2108924118. [PMID: 34649995 DOI: 10.1073/pnas.2108924118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2021] [Indexed: 11/18/2022] Open
Abstract
It is commonly believed that the energy bands of typical collinear antiferromagnets (AFs), which have zero net magnetization, are Kramers spin-degenerate. Kramers nondegeneracy is usually associated with a global time-reversal symmetry breaking (e.g., via ferromagnetism) or with a combination of spin-orbit interaction and broken spatial inversion symmetry. Recently, another type of spin splitting was demonstrated to emerge in some collinear magnets that are fully spin compensated by symmetry, nonrelativistic, and not even necessarily noncentrosymmetric. These materials feature nonzero spin density staggered in real space as seen in traditional AFs but also spin splitting in momentum space, generally seen only in ferromagnets. This results in a combination of materials characteristics typical of both ferromagnets and AFs. Here, we discuss this recently discovered class with application to a well-known semiconductor, FeSb2, and predict that with certain alloying, it becomes magnetic and metallic and features the aforementioned magnetic dualism. The calculated energy bands split antisymmetrically with respect to spin-degenerate nodal surfaces rather than nodal points, as in the case of spin-orbit splitting. The combination of a large (0.2-eV) spin splitting, compensated net magnetization with metallic ground state, and a specific magnetic easy axis generates a large anomalous Hall conductivity (∼150 S/cm) and a sizable magnetooptical Kerr effect, all deemed to be hallmarks of nonzero net magnetization. We identify a large contribution to the anomalous response originating from the spin-orbit interaction gapped anti-Kramers nodal surfaces, a mechanism distinct from the nodal lines and Weyl points in ferromagnets.
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