Layer‐controlled nonlinear terahertz valleytronics in two‐dimensional semimetal and semiconductor PtSe2

Author:

Hemmat Minoosh1,Ayari Sabrine1,Mičica Martin1,Vergnet Hadrien1,Guo Shasha2,Arfaoui Mehdi3,Yu Xuechao4ORCID,Vala Daniel56ORCID,Wright Adrien1,Postava Kamil56,Mangeney Juliette1,Carosella Francesca1,Jaziri Sihem2,Wang Qi Jie7,Liu Zheng2ORCID,Tignon Jérôme1,Ferreira Robson1,Baudin Emmanuel1,Dhillon Sukhdeep1ORCID

Affiliation:

1. Laboratoire de Physique de l'Ecole normale supérieure, ENS Université PSL, CNRS, Sorbonne Université, Université de Paris‐Cité Paris France

2. School of Materials Science and Engineering Nanyang Technological University Singapore Singapore

3. Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences de Tunis Université Tunis El Manar, Campus Universitaire Tunis Tunisia

4. Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Suzhou Institute of Nano‐Tech and Nano‐Bionics Chinese Academy of Sciences Suzhou Jiangsu the People's Republic of China

5. IT4Innovations, National Supercomputing Center VSB—Technical University of Ostrava Ostrava‐Poruba Czech Republic

6. Faculty of Materials Science and Technology VSB—Technical University of Ostrava Ostrava‐Poruba Czech Republic

7. School of Electrical and Electronic Engineering & School of Physical and Mathematical Sciences The Photonics Institute, Nanyang Technological University Singapore Singapore

Abstract

AbstractPlatinum diselenide () is a promising two‐dimensional (2D) material for the terahertz (THz) range as, unlike other transition metal dichalcogenides (TMDs), its bandgap can be uniquely tuned from a semiconductor in the near‐infrared to a semimetal with the number of atomic layers. This gives the material unique THz photonic properties that can be layer‐engineered. Here, we demonstrate that a controlled THz nonlinearity—tuned from monolayer to bulk —can be realized in wafer size polycrystalline through the generation of ultrafast photocurrents and the engineering of the bandstructure valleys. This is combined with the layer interaction with the substrate for a broken material centrosymmetry, permitting a second order nonlinearity. Further, we show layer dependent circular dichroism, where the sign of the ultrafast currents and hence the phase of the emitted THz pulse can be controlled through the excitation of different bandstructure valleys. In particular, we show that a semimetal has a strong dichroism that is absent in the monolayer and few layer semiconducting limit. The microscopic origins of this TMD bandstructure engineering are highlighted through detailed DFT simulations, and shows the circular dichroism can be controlled when becomes a semimetal and when the K‐valleys can be excited. As well as showing that is a promising material for THz generation through layer controlled optical nonlinearities, this work opens up a new class of circular dichroism materials beyond the monolayer limit that has been the case of traditional TMDs, and impacting a range of domains from THz valleytronics, THz spintronics to harmonic generation.image

Funder

H2020 Future and Emerging Technologies

H2020 Excellent Science

Agence Nationale de la Recherche

National Research Foundation Singapore

Publisher

Wiley

Subject

Materials Chemistry,Surfaces, Coatings and Films,Materials Science (miscellaneous),Electronic, Optical and Magnetic Materials

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