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Persistent Photogenerated State Attained by Femtosecond Laser Irradiation of Thin Td‑MoTe2

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journal contribution
posted on 05.08.2022, 21:40 authored by Meixin Cheng, Shazhou Zhong, Nicolas Rivas, Tina Dekker, Ariel Alcides Petruk, Patrick Gicala, Kostyantyn Pichugin, Fangchu Chen, Xuan Luo, Yuping Sun, Adam W. Tsen, Germán Sciaini
Laser excitation has emerged as a means to expose hidden states of matter and promote phase transitions on demand. Such laser-induced transformations are often rendered possible owing to the delivery of spatially and/or temporally manipulated light, carrying energy quanta well above the thermal background. Here, we report time-resolved broadband femtosecond (fs) transient absorption measurements on thin flakes of the Weyl semimetal candidate Td-MoTe2 subjected to various levels and schemes of fs-photoexcitation. Our results reveal that impulsive fs-laser irradiation alters the interlayer behavior of the low temperature Td phase as evidenced by the persistent disappearance of its characteristic coherent 1A1 ≈ 13 cm–1 shear phonon mode. We found that this structural transformation is likely related to lattice strain formation, withstands thermal cycling, and can be reverted to the 1T′ phase by fs-laser treatment at room temperature. Since interlayer shear strain was encountered to lead to a topologically distinct phase in an analogous compound, our work opens the door to the reversible optical control of electronic properties in this class of materials.