Hybrid Origin of Polarization in Superlubric van der Waals MoS2/h-BN/MoS2 Heterostructures
by
1/2-2 - Aula C
Dipartimento di Fisica e Astronomia - Edificio Marzolo
Two-dimensional (2D) sliding ferroelectricity typically arises from the breaking of inversion
symmetry in stacked van der Waals (vdW) materials, such as bilayer MoS2
or h-BN, where
switchable electric polarization is coupled to interlayer sliding. Recently, the concept of
"superlubric sliding ferroelectricity" was proposed in lattice-mismatched MoS2
/h-BN/MoS2
(MBM) heterostructures. Leveraging incommensurate vdW contacts, these structures achieve
an ultra-low switching barrier of ~0.2 meV/atom with only a marginal reduction in polarization.
However, the physical mechanism governing this phenomenon remains unclear. Using firstprinciples calculations, we reveal that the ferroelectric polarization in superlubric MBM
heterostructures originates critically from the structural buckling of the h-BN layer induced by
lattice relaxation. Distinct from conventional sliding ferroelectricity, which is driven solely by
stacking-induced symmetry breaking, the mechanism in these superlubric heterostructures is
neither purely ionic nor entirely electronic. This hybrid origin underscores the critical role of
intralayer structural degrees of freedom. This finding provide new physical insights and an
expanded design space for developing ultra-low-loss and picosecond-response sliding
ferroelectric devices.