Charge density wave activated excitons in TiSe2–MoSe2 heterostructures
Jaydeep Joshi,
Benedikt Scharf,
Igor Mazin,
Sergiy Krylyuk,
Daniel J. Campbell,
Johnpierre Paglione,
Albert Davydov,
Igor Žutić,
Patrick M. Vora
Affiliations
Jaydeep Joshi
Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030, USA
Benedikt Scharf
Institute for Theoretical Physics and Astrophysics and Würzburg-Dresden Cluster of Excellence ct.qmats, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
Igor Mazin
Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030, USA
Sergiy Krylyuk
Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
Daniel J. Campbell
Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
Johnpierre Paglione
Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
Albert Davydov
Quantum Science and Engineering Center, George Mason University, Fairfax, Virginia 22030, USA
Igor Žutić
Department of Physics, University at Buffalo, Buffalo, New York 14260, USA
Patrick M. Vora
Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030, USA
Layered materials enable the assembly of a new class of heterostructures where lattice-matching is no longer a requirement. Interfaces in these heterostructures therefore become a fertile ground for unexplored physics as dissimilar phenomena can be coupled via proximity effects. In this article, we identify an unexpected photoluminescence (PL) peak when MoSe2 interacts with TiSe2. A series of temperature-dependent and spatially resolved PL measurements reveal that this peak is unique to the TiSe2–MoSe2 interface, is higher in energy compared to the neutral exciton, and exhibits exciton-like characteristics. The feature disappears at the TiSe2 charge density wave transition, suggesting that the density wave plays an important role in the formation of this new exciton. We present several plausible scenarios regarding the origin of this peak that individually capture some aspects of our observations but cannot fully explain this feature. These results therefore represent a fresh challenge for the theoretical community and provide a fascinating way to engineer excitons through interactions with charge density waves.
