Exploring Quantum Materials through Anion Chemistry and External Stimuli
Hiroshi Takatsu
Abstract
Conventional solid-state chemistry controls crystal structures and electronic states through chemical composition and temperature. Mixed-anion chemistry expands this framework by combining anions with different size, charge, and bonding character, while external stimuli offer additional routes to access structures and phases that are difficult to reach by conventional synthetic conditions.
In this seminar, I will present examples from our recent work. First, in the oxyhydride EuVO2H, pressure and epitaxial strain induce intersite charge transfer between EuH and VO2 layers, resulting in metallization, enhanced ferromagnetism, and pronounced magnetic anisotropy [1-3]. Second, ionic-liquid gating offers a different way to control anion chemistry, enabling electrochemical F−-ion insertion into oxygen-deficient oxide films and yielding functional oxyfluorides [4]. Finally, a topochemical reaction transforms Mo2Ta2O11 into Mo3Ta2O10N through a double-to-single-layer conversion [5], which breaks the usual one-to-one structural correspondence between precursor and product structures and produces an itinerant two-dimensional kagomé system.
Together, these studies show how anion chemistry and external stimuli can reshape both reaction pathways and energy landscapes, providing access to structures and electronic states beyond the reach of conventional synthesis.
[1] M. Namba, H. Takatsu*, H. Kageyama*, et al., J. Am. Chem. Soc. 2023, 145, 21807-21816.
[2] M. Namba, H. Takatsu*, H. Kageyama*, et al., Chem. Mater. 2024, 36, 3918-3924.
[3] H. Takatsu*, M. Namba, H. Kageyama*, et al., Inorg. Chem. 2026, 65, 2767-2773.
[4] M. Namba, H. Takatsu*, H. Kageyama*, et al., Chem. Mater. 2024, 36, 2076-2084.
[5] R. Higuchi, H. Takatsu*, H. Kageyama*, et al., J. Am. Chem. Soc. 2025, 147, 27576-27585.
Contact : Shunsuke Sasaki (PMN)
