Discovery of an intermediate nematic state in a bilayer kagome metal ScV6Sn6
- Camron Farhang
- William R. Meier
- Weihang Lu
- Jiangxu Li
- Yudong Wu
- Shirin Mozaffari
- Richa P. Madhogaria
- Yang Zhang
- David Mandrus
- Jing Xia
2025-08-23
Nematicity, spontaneous breaking of rotational symmetry, is a ubiquitous phenomenon in correlated quantum matter. Here we show a phase transition in high-quality ScV 6 Sn 6 bilayer kagome metal at a temperature $${T}^{*}$$ T * , occurring seven Kelvins below the charge density wave transition at $${T}_{{CDW}}$$ T C D W , as indicated by thermodynamic, transport, and optical measurements. This emerging intermediate phase does not exhibit spontaneous time-reversal-symmetry breaking, as evidenced by zero-field Sagnac interferometry. However, it displays a strong, spontaneous in-plane anisotropy between $${T}^{*}$$ T * and $${T}_{{CDW}}$$ T C D W , revealed by transport and optical polarization rotation measurements. A pronounced depolarization effect detected by the Sagnac interferometer further confirms its nematic nature. Unlike AV 3 Sb 5 , this phase, alongside the recently discovered intra-unit cell nematic order at lower temperatures, presents a diverse landscape of nematicities at multiple length and temperature scales. Our findings highlight ScV 6 Sn 6 as a prime candidate for realizing symmetry-breaking phases driven by charge density competition, kagome physics, and Van Hove singularities.