Microscopic mechanism of the zero in-plane-field resistance peak

Determine the microscopic mechanism by which an in-plane magnetic field near zero produces excess longitudinal resistance across existing magnetic domain walls in the valley-polarized quarter-metal state of twisted double bilayer graphene.

Background

The paper establishes that the anomalous zero-in-plane-field resistance peak is associated with metastable magnetic domains in the valley-polarized quarter-metal state of twisted double bilayer graphene. Because spin and valley polarization are coupled by spin-orbit interaction, the authors argue that adjacent domains may also possess oppositely oriented spin polarizations.

The authors discuss current-driven precession of spin textures at domain walls as a speculative explanation. At zero in-plane field, weakly pinned in-plane domain-wall moments could precess under spin-transfer torque, whereas a finite in-plane field could pin those moments and suppress the resulting excess resistance. However, the available data do not identify this microscopic transport mechanism unambiguously.