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arXiv · 1602.03568

Imaging Spin Dynamics in Monolayer WS2 by Time-Resolved Kerr Rotation Microscopy

Elizabeth J. Bushong·Michael Newburger·Yunqiu·Luo·Kathleen M. McCreary·Simranjeet Singh·Iwan B. Martin·Edward J. Cichewicz Jr.·Berend T. Jonker·Roland K. Kawakami
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Abstract

Monolayer transition metal dichalcogenides (TMD) have immense potential for future spintronic and valleytronic applications due to their two-dimensional nature and long spin/valley lifetimes. We investigate the origin of these long-lived states in n-type WS2 using time-resolved Kerr rotation microscopy and photoluminescence microscopy with ~1 micron spatial resolution. Comparing the spatial dependence of the Kerr rotation signal and the photoluminescence reveals a correlation with neutral exciton emission, which is likely due to the transfer of angular momentum to resident conduction electrons with long spin/valley lifetimes. In addition, we observe an unexpected anticorrelation between the Kerr rotation and trion emission, which provides evidence for the presence of long-lived spin/valley-polarized dark trions. We also find that the spin/valley polarization in WS2 is robust to magnetic fields up to 700 mT, indicative of spins and valleys that are stabilized with strong spin-orbit fields.

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Elizabeth J. Bushong, Michael Newburger, Yunqiu, Luo, Kathleen M. McCreary, Simranjeet Singh, Iwan B. Martin, Edward J. Cichewicz Jr., Berend T. Jonker, Roland K. Kawakami. 2016-02-10. Imaging Spin Dynamics in Monolayer WS2 by Time-Resolved Kerr Rotation Microscopy. https://doi.org/10.1088/2053-1583/aa98ae

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