DQMP Forum - Van der Waals Interface Field-effect Transistors as Tunable Light Sources - STM/STS Studies of Bi2Sr2CaCu2O8+δ High-TC Cuprate Superconductor

02.11.2021 13:00 – 14:00

Van der Waals Interface Field-effect Transistors as Tunable Light Sources
Hugo Henck (Group of prof. Morpurgo)

Assembling semiconductors in type-II interfaces is promising for optoelectronics as the spectral response of the interlayer excitons can be tailored over a broad range by changing the constituents of the het-erostructure. Recent works have shown that engineering van der Waals (vdW) heterostructures based on crystals that have the bottom of the conduction band and the top of the valence band at the Γ-point provide a robust method to tune photoluminescence at various energies depending on the constituents and their thicknesses [1]. Here we fabricated and investigated the first electrical devices of this type of interfaces (i.e. InSe/TMD bilayer). By operating the devices such that a p-i-n junction forms in the interfacial channel, we observe bright electroluminescence from interlayer excitons. By tuning the voltage across the interface we are able to modulate the emission energy of the EL over several hundreds of meV. This illustrates that tailored vdW interfaces provide a very attractive platform for tunable radiation sources that cover a very broad frequency spectrum as well as for the study of excitonic dynamic [2–4].

STM/STS Studies of Bi2Sr2CaCu2O8+δ High-TC Cuprate Superconductor
Tejas Singar (group of prof. Renner)

High temperature cuprate superconductors keep attracting the attention of the scientific community. Known for their complex phase diagram, these materials present an opportunity to study the mechanisms driving different electronic phases. Among them, the electronic orders found at low hole doping are particularly puzzling; while they are believed to be intimately linked to the unconventional normal state, their interplay with the superconducting phase is far from being fully understood.
In this talk, I will discuss some of our recent STM/STS studies of Bi2Sr2CaCu2O8+δ. The detection of periodic patterns with STM is particularly challenging in heavily-underdoped single crystals due to their intrinsic electronic inhomogeneities. We will present first results, where we use very low bias dependent imaging to disentangle dispersionless charge density waves from dispersive quasiparticle interference (QPI) patterns.

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Bâtiment: Ecole de Physique

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