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arXiv · 1705.04866

Giant spin-splitting and gap renormalization driven by trions in single-layer WS$_2$/h-BN heterostructures

Jyoti Katoch·Søren Ulstrup·Roland J. Koch·Simon Moser·Kathleen M. McCreary·Simranjeet Singh·Jinsong Xu·Berend T. Jonker·Roland K. Kawakami·Aaron Bostwick·Eli Rotenberg·Chris Jozwiak
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Abstract

In two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs), new electronic phenomena such as tunable band gaps and strongly bound excitons and trions emerge from strong many-body effects, beyond spin-orbit coupling- and lattice symmetry-induced spin and valley degrees of freedom. Combining single-layer (SL) TMDs with other 2D materials in van der Waals heterostructures offers an intriguing means of controlling the electronic properties through these many-body effects via engineered interlayer interactions. Here, we employ micro-focused angle-resolved photoemission spectroscopy (microARPES) and in-situ surface doping to manipulate the electronic structure of SL WS$_2$ on hexagonal boron nitride (WS$_2$/h-BN). Upon electron doping, we observe an unexpected giant renormalization of the SL WS$_2$ valence band (VB) spin-orbit splitting from 430~meV to 660~meV, together with a band gap reduction of at least 325~meV, attributed to the formation of trionic quasiparticles. These findings suggest that the electronic, spintronic and excitonic properties are widely tunable in 2D TMD/h-BN heterostructures, as these are intimately linked to the quasiparticle dynamics of the materials.

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Jyoti Katoch, Søren Ulstrup, Roland J. Koch, Simon Moser, Kathleen M. McCreary, Simranjeet Singh, Jinsong Xu, Berend T. Jonker, Roland K. Kawakami, Aaron Bostwick, Eli Rotenberg, Chris Jozwiak. 2017-05-13. Giant spin-splitting and gap renormalization driven by trions in single-layer WS$_2$/h-BN heterostructures. https://doi.org/10.1038/s41567-017-0033-4

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