Evidence of spin-valley texture in Twisted Double Bilayer Graphene

Twisted van der Waals heterostructures are celebrated platforms for realizing flat electronic bands, in which electron-electron interactions can lead to correlated phases. Dual gated heterostructures composed of twisted double bilayer graphene have demonstrated a particularly rich landscape, exhibiting valley and spin polarized states, nematic order and spontaneous time reversal symmetry breaking (TRSB). In this work we report on an anomalous resistivity response to the application of magnetic fields parallel to the device plane, for the same gate voltage settings where orbital TRSB is observed: a narrow resistance peak is observed when crossing zero in-plane field, which may increase the sample resistance by up to a factor of 3. The feature is suppressed by just a few millitesla of in-plane field, but only weakly sensitive to out-of-plane field. The resistance peak height decreases with increasing temperature and is not observed above 500 mK. Such extreme sensitivity to in-plane field is not expected for an orbital magnet; these observations hint at an underlying spin-valley texture in TDBG.