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Maximilian Tomoscheit

Publications and source records attributed to Maximilian Tomoscheit.

3 recordsLinked to original sources

Twist-angle Control of Nonlinear Interference in a ZnO Nanowire/Monolayer WSe$_2$ Hybrid Structure

Nanoscale devices that integrate materials of different dimensionalities (0D, 1D, and 2D) hold great potential for advanced applications in photonics and optoelectronics. A fundamental requirement for the development of such devices is the engineering and control of light-matter interactions beyond the simple enhancement or quenching of linear and nonlinear optical emission. In this study, we demonstrate control over nanoscale light-matter interactions by achieving twist-angle tunability of the nonlinear optical response in a hybrid system composed of a ZnO nanowire and a monolayer of WSe$_2$. By varying the relative orientation between the ZnO polar axis and the WSe$_2$ crystal axes, we realize both constructive and destructive interference in second-harmonic generation, as well as full material selectivity in second harmonic polarization-dependent measurements. These outcomes arise from the distinct dimensionalities and symmetries of the hybrid constituents, underscoring the generality of our approach. Thus, our work presents an advanced framework for the design and control of nonlinear light-matter interactions in nanoscale hybrid devices, thereby paving the way for their future use in photonic and optoelectronic technologies.

physics.optics

Long-lived Photoluminescence of Photostable One-dimensional Picoperovskites

We study one-dimensional metal halide perovskite crystals encapsulated in single-wall nanotubes, so-called picoperovskites, using optical spectroscopy. Polarized micro-photoluminescence (PL) reveals bright emission from aligned bundles of picoperovskites with clear linear polarization along the bundle axis. This emission is red-shifted with respect to bulk perovskite samples using the same constituents. Temperature-dependent, time-resolved micro-PL shows extraordinarily long PL lifetimes of the picoperovskites at low temperatures, reaching several hundred nanoseconds and exceeding those of bulk perovskites by two orders of magnitude.

cond-mat.mes-hall

Rapid spin depolarization in the layered 2D Ruddlesden Popper perovskite (BA)(MA)PbI

We report temperature-dependent spectroscopy on the layered (n=4) two-dimensional (2D) Ruddlesden-Popper perovskite (BA)(MA)PbI. Helicity-resolved steady-state photoluminescence (PL) reveals no optical degree of polarization. Time-resolved PL shows a photocarrier lifetime on the order of nanoseconds. From simultaneaously recorded time-resolved differential reflectivity (TR$Δ$R) and time-resolved Kerr ellipticity (TRKE), a photocarrier lifetime of a few nanoseconds and a spin dephasing time on the order of picoseconds was found. This stark contrast in lifetimes clearly explains the lack of spin polarization in steady-state PL. While we observe clear temperature-dependent effects on the PL dynamics that can be related to structural dynamics, the spin dephasing is nearly T-independent. Our results highlight that spin dephasing in 2D (BA)(MA)PbI occurs at time scales faster than the exciton recombination time, which poses a bottleneck for applications aimingto utilize this degree of freedom.

cond-mat.mes-hall