Electronic devices exploring carrier transport with spin and valley degree of freedom have emerged as promising candidates for next-generation information storage and transport, since pure spin and valley currents do not accompany energy dissipation associated with Joule heating. The spin and valley degree of freedom of electrons in two-dimensional (2D) transition metal dichalcogenides (TMDs) have been extensively studied by theory, optical and optoelectronic experiments. The ability to electrically generate and detect such pure spin and valley currents in these materials is of particular importance. In this talk, we first report that valley current can be electrically induced and detected through the valley Hall effect and inverse valley Hall effect, respectively, in monolayer molybdenum disulfide. We compare temperature and channel length dependence of non-local electrical signals in monolayer and multi-layer samples to distinguish the valley Hall effect from classical Ohmic contributions. Significantly, valley transport is observed over four-micron distance in monolayer samples at room temperature. We then study the valley coupled spin generation in monolayer tungsten disulfide and spin diffusion in a 2D stack device. Our device design approach provides a unique way to integrate charge, spin and valley degrees of freedom, which can be useful for emerging valleytronic applications.

Zhihong Chen received her B.S. degree in physics from Fudan University in 1998, and her Ph.D. degree in physics from the University of Florida in 2003. After two years of postdoctoral research at IBM T.J. Watson research center, she became a research staff member in the Physical Science Department. Her research focused on design and fabrication of high performance carbon based devices and circuits. In 2008, she was appointed as the manager of the Carbon Technology Group at IBM, where she was in charge of evaluating the potential of carbon materials and the development of novel carbon based technologies for commercial applications. She joined the School of Electrical and Computer Engineering at Purdue University in 2010 as an Associate Professor, and has become a Full Professor since 2017. Her research interests focus on device and circuit designs for beyond-CMOS applications. She has become the Director of the SRC nCORE NEW LIMITS Center since 2018, and Associated Director of Research for Birck Nanotechnology Center in 2019. She is an Associate Editor of IEEE Electron Device Letters.

Purdue Quantum and Science Engineering Institute, Tohoku University, Discovery Park

Researchers should cite this work as follows:

• Zhihong Chen (2020), "2D Valley-Spin Transport in Transition Metal Dichalcogenides," https://nanohub.org/resources/33422.

  BibTex | EndNote

1. 2D materials and devices
2. carrier transport
3. Hall effect
4. nanoelectronics
5. nanoMFG Node
6. spintronics