  In conventional ferroelectric materials, polarization is an intrinsic
property limited by bulk crystallographic structure and symmetry. Recently, it
has been demonstrated that polar order can also be accessed using inherently
non-polar van der Waals materials through layer-by-layer assembly into
heterostructures, wherein interfacial interactions can generate spontaneous,
switchable polarization. Here, we show that introducing interlayer rotations in
multilayer vdW heterostructures modulates both the spatial ordering and
switching dynamics of polar domains, engendering unique tunability that is
unparalleled in conventional bulk ferroelectrics or polar bilayers. Using
operando transmission electron microscopy we show how changing the relative
rotations of three WSe2 layers produces structural polytypes with distinct
arrangements of polar domains, leading to either a global or localized
switching response. Introducing uniaxial strain generates structural anisotropy
that yields a range of switching behaviors, coercivities, and even tunable
biased responses. We also provide evidence of physical coupling between the two
interfaces of the trilayer, a key consideration for controlling switching
dynamics in polar multilayer structures more broadly.
