Abstract
Coupling degrees of freedom of distinct nature plays a critical role in numerous physical phenomena. The recent emergence of layered materials provides a laboratory for studying the interplay between internal quantum degrees of freedom of electrons. Here we report new coupling phenomena connecting real spin with layer pseudospins in bilayer WSe 2. In polarization-resolved photoluminescence measurements, we observe large spin orientation of neutral and charged excitons by both circularly and linearly polarized excitation, with the trion spectrum splitting into a doublet at large vertical electrical field. These observations can be explained as a locking of spin and layer pseudospin in a given valley, where the doublet implies an electrically induced spin splitting. The observed distinctive behaviour of the trion doublet under polarized excitation further provides spectroscopic evidence of interlayer and intralayer trion species, a promising step towards optical manipulation in van der Waals heterostructures through interlayer excitons.
| Original language | English |
|---|---|
| Pages (from-to) | 130-134 |
| Number of pages | 5 |
| Journal | Nature Physics |
| Volume | 10 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 2014 |
Funding
The authors wish to acknowledge G. Liu and X. Wu for helpful information on the bilayer band structure, and D. Cobden for useful comments. This work is mainly supported by US DoE, BES, Division of Materials Sciences and Engineering (DE-SC0008145). A.M.J. is partially supported by a NSF graduate fellowship (DGE-0718124). H.Y. and W.Y. were supported by the Research Grant Council (HKU705513P) of the government of Hong Kong, and the Croucher Foundation under the Croucher Innovation Award. N.J.G., J.Y. and D.G.M. were supported by US DoE, BES, Materials Sciences and Engineering Division. Device fabrication was completed at the University of Washington Microfabrication Facility and NSF-funded Nanotech User Facility. Second harmonic generation is done at Garvey Imaging Core of the Institute for Stem Cell and Regenerative Medicine.