NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

PUBLICATIONS

Trion Valley Coherence in Monolayer Semiconductors

Published

Author(s)

Kai Hao, Lixiang Xu, Wu Fengcheng, Philip Nagler, Kha Tran, Xin Ma, Tobias Korn, Allan H. MacDonald, Xiaoqin Li, Galan Moody

Abstract

The emerging field of valleytronics aims to exploit the valley pseudospin of electrons residing near Bloch band extrema as an information carrier. Recent experiments demonstrating optical generation and manipulation of exciton valley coherence (the superposition of electron-hole pairs at opposite valleys) in monolayer transition metal dichalcogenides (TMDs) provide a critical step towards control of this quantum degree of freedom. The charged exciton (trion) in TMDs is an intriguing alternative to the neutral exciton for control of valley pseudospin because of its long spontaneous recombination lifetime, its robust valley polarization, and its coupling to residual electronic spin. Trion valley coherence has however been unexplored due to experimental challenges in accessing it spectroscopically. In this work we employ ultrafast two-dimensional coherent spectroscopy to resonantly generate and detect trion valley coherence in monolayer MoSe2 demonstrating that it persists for a few-hundred femtoseconds. We conclude that the underlying mechanisms limiting trion valley coherence are fundamentally different from those applicable to exciton valley coherence. Based on these observations, we suggest possible strategies for extending valley coherence times in two-dimensional materials.
Citation
2D Materials
Volume
4
Pub Type
Journals

Download Paper

https://doi.org/10.1088/2053-1583/aa70f9
Local Download

Keywords

valleytronics, two-dimensional materials, charged exciton, coherence
Semiconductors, Quantum information science, Optical physics and communications, Nanometrology, Nanomaterials and Condensed matter

Citation

Hao, K. , Xu, L. , Fengcheng, W. , Nagler, P. , Tran, K. , Ma, X. , Korn, T. , MacDonald, A. , Li, X. and Moody, G. (2017), Trion Valley Coherence in Monolayer Semiconductors, 2D Materials, [online], https://doi.org/10.1088/2053-1583/aa70f9, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=922272 (Accessed October 14, 2025)

Issues

If you have any questions about this publication or are having problems accessing it, please contact [email protected].

Created May 21, 2017, Updated October 12, 2021
Was this page helpful?