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작성일 : 18-12-06 17:27
2018년 12월 12일 콜로퀴움 공지
 글쓴이 : 응용물리학과
조회 : 10  
   붙임1_세미나공고(181205).pdf (221.8K) [2] DATE : 2018-12-06 17:27:24

안녕하세요. 콜로퀴움 안내입니다.
 

 
일시: 12월 12일 수요일 오후 4시 30분
장소: 전자정보대학 211-2호
연사: 이지은 교수 (아주대학교 물리학과)

제목:  Optical imaging of the valley dependent electron transport in MoS2
 
 Atomically thin crystals, such as monolayer transition metal dichalcogenides (TMDs), provide a new platform to investigate electrons in low dimensional solid state systems. In these materials, two inequivalent energy band extrema occur at the edges of the Brillouin zone, known as valleys, which serve as a binary degree of freedom of electrons similar like spins. The unique control of valley pseudospins by optical and electrical means are not only fundamentally interesting, but may also find applications in valley-based electronics and optoelectronics.
In this talk, we discuss methods to manipulate the valley polarization in 2-dimensional TMD materials. First, we describe the observation of the valley Hall effect in monolayer molybdenum disulfide (MoS2),  in which the valley current is generated transverse to the charge current. We use optical techniques to directly image the valley polarization accumulated at the edges of MoS2 channel with spatial resolution. We will also discuss the possibility to tune the valley Hall conductivity by controlling the crystal’s inversion symmetry in bilayer. Second, we apply strain to monolayer MoS2 to break the crystal’s 3-fold rotational symmetry which leads to the generation of valley magnetoelectricity. The observed valley magnetization switches the sign when the in-plane bias direction flips and its magnitude scales with the amount of channel current. We discuss the dependence of the observed magnetization on bias, gate, and strain.