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arXiv · 2206.10631

Tunable spin and valley excitations of correlated insulators in $Γ$-valley moiré bands

Benjamin A. Foutty·Jiachen Yu·Trithep Devakul·Carlos R. Kometter·Yang Zhang·Kenji Watanabe·Takashi Taniguchi·Liang Fu·Benjamin E. Feldman
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Abstract

Moiré superlattices formed from transition metal dichalcogenides (TMDs) have been shown to support a variety of quantum electronic phases that are highly tunable using applied electromagnetic fields. While the valley character of the low-energy states dramatically affects optoelectronic properties in the constituent TMDs, this degree of freedom has yet to be fully explored in moiré systems. Here, we establish twisted double bilayer WSe$_2$ as an experimental platform to study electronic correlations within $Γ$-valley moiré bands. Through a combination of local and global electronic compressibility measurements, we identify charge-ordered phases at multiple integer and fractional moiré band fillings $ν$. By measuring the magnetic field dependence of their energy gaps and the chemical potential upon doping, we reveal spin-polarized ground states with novel spin polaron quasiparticle excitations. In addition, an applied displacement field allows us to realize a new mechanism of metal-insulator transition at $ν= -1$ driven by tuning between $Γ$- and $K$-valley moiré bands. Together, our results demonstrate control over both the spin and valley character of the correlated ground and excited states in this system.

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Benjamin A. Foutty, Jiachen Yu, Trithep Devakul, Carlos R. Kometter, Yang Zhang, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Benjamin E. Feldman. 2023-10-23. Tunable spin and valley excitations of correlated insulators in $Γ$-valley moiré bands. https://doi.org/10.1038/s41563-023-01534-z

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