Tunable spin and valley excitations of correlated insulators in -valley moire bands

Moire superlattices formed from transition metal dichalcogenides support a variety of quantum electronic phases that are highly tunable using applied electromagnetic fields. While the valley degree of freedom affects optoelectronic properties in the constituent transition metal dichalcogenides, it has yet to be fully explored in moire systems. Here we establish twisted double-bilayer WSe2 as an experimental platform to study electronic correlations within Gamma-valley moire bands. Through local and global electronic compressibility measurements, we identify charge-ordered phases at multiple integer and fractional moire fillings. By measuring the magnetic field dependence of their energy gaps and the chemical potential upon doping, we reveal spin-polarized ground states with spin-polaron quasiparticle excitations. In addition, an applied displacement field induces a metal-insulator transition driven by tuning between Gamma- and K-valley moire bands. Our results demonstrate control over the spin and valley character of the correlated ground and excited states in this system. Electronic compressibility measurements of twisted double-bilayer WSe2 reveal correlated insulators with spin-polaron charged excitations, as well as close competition between moire bands at Gamma and K valleys.