  Uniaxial and biaxial strain approaches are usually implemented to switch the
ferroelastic states, which play a key role in the application of the ferroics
and shape memory materials. In this work, by using the first-principles
calculations, we found not only uniaxial strain, but also shear strain can
induce a novel ferroelastic switching, in which the van der Waals (vdW) layered
direction rotates with the ferroelastic transition in layered bulk PdSe2. The
shear strain induces ferroelastic switching with three times amplitude smaller
than uniaxial strain. The novel three-states ferroelastic switching in layered
PdSe2 also occurs under shear strain. Our result shows that the shear strain
could be used as an effective approach for manipulating the functionalities of
layered materials in potential device applications.
