Linear resistivity at van Hove singularities in twisted bilayer WSe2

Different mechanisms driving a linear temperature dependence of the resistivity rho - T at van Hove singularities (VHSs) or metal- insulator transitions when doping a Mott insulator are being debated intensively with competing theoretical proposals. We experimentally investigate this using the exceptional tunability of twisted bilayer (TB) WSe2 by tracking the parameter regions where linear-in- Tresistivity is found in dependency of displacement fields, filling, and magnetic fields. We find that even when the VHSs are tuned rather far away from the half-filling point and the Mott insulating transition is absent, the T- linear resistivity persists at the VHSs. When doping away from the VHSs, the T- linear behavior quickly transitions into a Fermi liquid behavior with a T2 relation. No apparent dependency of the linear-in- T resistivity, besides a rather strong change of prefactor, is found when applying displacement fields as long as the filling is tuned to the VHSs, including D - 0.28 V/nm where a high-order VHS is expected. Intriguingly, such non-Fermi liquid linear-in- T resistivity persists even when magnetic fields break the spin- degeneracy of the VHSs at which point two linear in Tregions emerge, for each of the split VHSs separately. This points to a mechanism of enhanced scattering at generic VHSs rather than only at high-order VHSs or by a quantum critical point during a Mott transition. Our findings provide insights into the many-body consequences arising out of VHSs, especially the non-Fermi liquid behavior found in moir & eacute; materials.