Unexpected stabilization of a single-q charge density wave in pristine 1T-TiSe2

Over the past decade, studies revisiting the classical charge-density-wave system 1T-TiSe₂, long understood to host the 2 × 2 triple-q order with equivalent subcomponents, have suggested that these subcomponents may not be identical, challenging a 50-year-old paradigm. Here, we demonstrate not only that these subcomponents are non-identical but also that they develop sequentially rather than simultaneously. By tracking folded-band features, angle-resolved photoemission spectroscopy reveals that a unidirectional 2 × 1 single-q order stabilizes first, while the other two components emerge sequentially at lower temperatures, completing the triple-q phase. Our free-energy analysis explains this hierarchy through repulsive coupling among the three subcomponents, as supported by first-principles calculations incorporating phonon anharmonicity. Consequently, the three subcomponents are inequivalent in both phase and amplitude. These results reconcile reported symmetry breaking and differing characteristic temperatures and establish a framework in which ostensibly simple, high-symmetry charge-density order emerges from temperature-dependent competition and cooperation among inequivalent subcomponents. The authors show that the subcomponents of the charge density wave in 1T-TiSe₂ are unequal and set in one by one, beginning with an unexpected unidirectional state.

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Publication Details

Journal
Nature Communications
Published
2026-09-29
DOI
https://doi.org/10.1038/s41467-026-78072-0
Primary Topic
2D Materials and Applications
Type
article
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article

Unexpected stabilization of a single-q charge density wave in pristine 1T-TiSe2

Sae Hee Ryu, Kimoon Han, Eli Rotenberg, Yeongkwan Kim et al.
Nature Communications
2D Materials and Applications
article

Unexpected stabilization of a single-q charge density wave in pristine 1T-TiSe2

Sae Hee Ryu, Kimoon Han, Eli Rotenberg, Yeongkwan Kim, Dong-Hui Lu, Chris M. Jozwiak, Jonathan D. Denlinger, Aaron Bostwick, Young Woo Choi, Chan‐young Lim, Makoto Hashimoto, Jaehun Cha, Gil Young Cho, Gyubin Lee, Seonggeon Gim, Dongsin Kim, Dongju Hwang, Yeojin Ahn, Mingi Jho
article en

Abstract

Over the past decade, studies revisiting the classical charge-density-wave system 1T-TiSe₂, long understood to host the 2 × 2 triple-q order with equivalent subcomponents, have suggested that these subcomponents may not be identical, challenging a 50-year-old paradigm. Here, we demonstrate not only that these subcomponents are non-identical but also that they develop sequentially rather than simultaneously. By tracking folded-band features, angle-resolved photoemission spectroscopy reveals that a unidirectional 2 × 1 single-q order stabilizes first, while the other two components emerge sequentially at lower temperatures, completing the triple-q phase. Our free-energy analysis explains this hierarchy through repulsive coupling among the three subcomponents, as supported by first-principles calculations incorporating phonon anharmonicity. Consequently, the three subcomponents are inequivalent in both phase and amplitude. These results reconcile reported symmetry breaking and differing characteristic temperatures and establish a framework in which ostensibly simple, high-symmetry charge-density order emerges from temperature-dependent competition and cooperation among inequivalent subcomponents. The authors show that the subcomponents of the charge density wave in 1T-TiSe₂ are unequal and set in one by one, beginning with an unexpected unidirectional state.

Nature Communications
Lawrence Berkeley National Laboratory (US), Sogang University (KR), Korea Advanced Institute of Science and Technology (KR), SLAC National Accelerator Laboratory (US), Institute for Basic Science (KR), Stanford Synchrotron Radiation Lightsource (US), Korea Basic Science Institute (KR), Advanced Light Source, Donostia International Physics Center (ES), Pusan National University (KR), Korea Institute of Science and Technology (KR)
Openalex Percentile: Top 26%
2D Materials and Applications
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