Layer-controlled nonlinear terahertz valleytronics in two-dimensional semimetal and semiconductor PtSe_(2)  

作　　者：Minoosh Hemmat Sabrine Ayari Martin Micica Hadrien Vergnet Shasha Guo Mehdi Arfaoui Xuechao Yu Daniel Vala Adrien Wright Kamil Postava Juliette Mangeney Francesca Carosella Sihem Jaziri Qi Jie Wang Zheng Liu Jérôme Tignon Robson Ferreira Emmanuel Baudin Sukhdeep Dhillon 

机构地区：[1]Laboratoire de Physique de l'Ecole normale supérieure,ENS,UniversitéPSL,CNRS,Sorbonne Université,Universitéde 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,Facultédes Sciences de Tunis,UniversitéTunis 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

出　　处：《InfoMat》2023年第11期49-63,共15页信息材料（英文）

基　　金：H2020 Future and Emerging Technologies,Grant/Award Number:964735;H2020 Excellent Science,Grant/Award Number:881603;Agence Nationale de la Recherche,Grant/Award Numbers:ANR-16-CE24-0023,ANR-2018-CE08-018-05;National Research Foundation Singapore,Grant/Award Number:NRF-CRP26-2021-0004;Region Ile de France;EquipMeso,Grant/Award Number:ANR-10-EQPX-29-01。

摘　　要：Platinum diselenide(PtSe_(2))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 nearinfrared 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 PtSe_(2)—can be realized in wafer size polycrystalline PtSe_(2)through the generation of ultrafast photocurrents and the engineering of the bandstructure valleys.This is combined with the PtSe_(2)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 PtSe_(2)becomes a semimetal and when the K-valleys can be excited.As well as showing that PtSe_(2)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.

关 键 词：2D transition metal dichalcogenides Dirac semimetal optical nonlinearities TERAHERTZ valleytronics 

分 类 号：TG14[一般工业技术—材料科学与工程] TN304[金属学及工艺—金属材料]