Multidirectional Reorientation in the Ferroelastic van der Waals Semimetal Molybdenum Ditelluride

Ferroelastic properties in two-dimensional materials have garnered significant attention due to their potential to control structural anisotropy, thereby influencing optical and electrical characteristics under external stress. Despite these potential applications, there remains a scarcity of reports on ferroelastic behavior in two-dimensional van der Waals materials. In this study, we investigate multidirectional ferroelastic reorientation in the two-dimensional van der Waals semimetallic phase of Molybdenum ditelluride (1T ' MoTe2). Employing a polymer encapsulation method, ferroelastic switching in 1T ' MoTe2 is examined via real-time polarized optical imaging under uniaxial strain. Polarized Raman spectroscopy confirms the orientation of Mo-Mo chains in original and reoriented domains, revealing 120 degrees rotational switching in reconstructed domains. Analysis using selective area electron diffraction and scanning transmission electron microscopy elucidate the atomic arrangements of original and reconstructed domains, including domain wall structures. Additionally, it is demonstrated that external uniaxial strain can differentiate between the stabilities of three equivalent states in 1T ' MoTe2, enabling manipulation of the orientation of Mo-Mo chains based on the direction of the applied strain. The findings highlight the capability for multidirectional ferroelastic reorientation in the two-dimensional semimetal MoTe2 through the application of uniaxial strain.