Twisted double bilayer graphene (tDBG) exhibits an anomalous Hall effect with hysteresis loops demonstrating spontaneously broken time-reversal symmetry, suggesting valley (orbital) ferromagnetism. Resistivity is strongly affected by in-plane magnetic fields, indicating spin-valley coupling or direct orbital coupling. The interplay of band topology and Coulomb interactions is investigated, revealing a correlated metallic state with broken spin and valley symmetries.

Manabendra Kuiri, Christopher Coleman, Zhenxiang Gao, Aswin Vishnuradhan, Kenji Watanabe, Takashi Taniguchi, Jihang Zhu, Allan H. MacDonald, Joshua Folk