Speaker
Description
The transition metal dichalcogenide 1$T$-TaS$_2$ is known for the formation of a charge density wave with a Star-of-David shaped reconstruction of Ta atoms [1], its spin liquid behaviour [2], and its non-equilibrium hidden state [3]. The charge density wave is connected to Mott physics and formation of a Doublon excitation [4]. In this talk recent results obtained on crystals with substitutional doping using Mo and W will be presented. While both dopants decrease the degree of commensurate charge density wave order, the Star-of-David reconstruction persists. However, the electronic response is strongly modified by doping as observed in the spectral variation induced by the charge density wave amplitude mode in time-resolved photoelectron emission spectroscopy [5]. Moreover, upon doping metastable electronic excitations are identified which are populated on femtosecond timescales and persist on various timescales up to minutes which allows active switching of the local population in scanning tunnelling experiments. This work demonstrates that substitutional doping of 1$T$-TaS$_2$ provides manifold opportunities to manipulate local electronic excitations in solid matter.
[1] B. Sipos et al., Nat. Mater. 7, 960 (2008).
[2] M. Klanjšek et al., Nat. Phys. 13, 1130 (2017).
[3] L. Stojchevska et al., Science 344, 177 (2014).
[4] M. Ligges et al., Phys. Rev. Lett. 120, 166401 (2018).
[5] J. Jayabalan et al., arXiv:2504.19961.