Stimuli‐Responsive Low‐Frequency Terahertz Absorption ON‐OFF Switchability in Spin‐Crossover Material
Thermal and optical-induced ON-OFF switchable materials show vast potential in various fields like sensors, spintronics, and electronic devices, but remain underexplored in the essential terahertz (THz) region. In this context, a unique 1D spin-crossover (SCO) network, {[Fe<sup>II</sup>(4-cyanopyridine)<sub>2</sub>][Hg<sup>II</sup>(µ-SCN)<sub>2</sub>(SCN)(4-cyanopyridine)]<sub>2</sub>}<sub>n</sub> (1), has been designed. Temperature-dependent crystallographic, magnetic, and THz absorption spectroscopic studies indicate an abrupt SCO phenomenon from a high-spin (HS) state to a complete or partial low-spin (LS) state, depending on the cooling rate. At low temperatures, the LS state can be converted into the metastable HS state via the light-induced excited spin-state trapping (LIESST) effect using visible or near-infrared lights. Both temperature and light reversibly modulate the THz absorbance (e.g., 0.82 and 1.37 THz) associated with phonons around Fe(II) centers, confirmed by first-principles calculations and photocrystallographic analysis. This work advances comprehension of the intersection between structures, THz properties, and external-stimuli switching effects and is pivotal for future THz device applications.
Authors
- Guillaume Chastanet (ORCID: https://orcid.org/0000-0001-6829-4066)
- Kenta Imoto (ORCID: https://orcid.org/0000-0002-6764-2484)
- Kunal Kumar (ORCID: https://orcid.org/0000-0002-2626-0615)
- Lulu Xiong
- Sumit Ranjan Maity (ORCID: https://orcid.org/0000-0002-8168-8024)
- Laurent Guérin (ORCID: https://orcid.org/0000-0002-0509-8444)
- Koji Nakabayashi (ORCID: https://orcid.org/0000-0002-5946-944X)
- Guanping Li (ORCID: https://orcid.org/0000-0001-5168-7998)
- Yuiga Nakamura (ORCID: https://orcid.org/0000-0003-3696-0997)
- Shin‐ichi Ohkoshi (ORCID: https://orcid.org/0000-0001-9359-5928)
- Nicholas F. Chilton (ORCID: https://orcid.org/0000-0002-8604-0171)
- Olaf Stefańczyk (ORCID: https://orcid.org/0000-0003-0955-5646)
- Maryam Alashoor (ORCID: https://orcid.org/0009-0007-7282-4454)
- Keiji Nakamura (ORCID: https://orcid.org/0000-0002-8500-9359)
Institutions
- Australian National University (AU)
- Centre National de la Recherche Scientifique (FR)
- Université de Bordeaux (FR)
- University of Macau (MO)
- University of Manchester (GB)
- SPring-8 (JP)
- Institut de Physique de Rennes (FR)
- Institut de Chimie de la Matière Condensée de Bordeaux (FR)
- Japan Synchrotron Radiation Research Institute (JP)
- Institut Polytechnique de Bordeaux (FR)
- Université de Rennes (FR)
- The University of Tokyo (JP)
Publication Details
- Journal
- Advanced Materials
- Published
- 2025-06-25
- DOI
- https://doi.org/10.1002/adma.202507457
- Citations
- 2
- Primary Topic
- Magnetism in coordination complexes
- Type
- article
- Field-Weighted Citation Impact
- 0.85
Funders
- Australian National University
- Ministry of Education, Culture, Sports, Science and Technology
- University of Tokyo
- Centre National de la Recherche Scientifique
- Iketani Science and Technology Foundation
- Japan Society for the Promotion of Science
- Japan Science and Technology Agency
- Advanced Low Carbon Technology Research and Development Program