arXiv subjects

Joerg Jinschek

Publications and source records attributed to Joerg Jinschek.

4 recordsLinked to original sources

arXiv2026

Role of self-coherence in single-electron phase contrast imaging

The extension of coherent lattice contrast into the energy loss region in high-resolution transmission electron microscopy (HRTEM) is described by a pulse-like electron-sample interaction in the energy/time uncertainty limit. It generates a wave packet by electron self-interference in any coherent-inelastic scattering event with energy loss. The width of this wave packet is characterized by a self-coherence length ls(ΔE) that is predictable because an intrinsic decoherence phase around one radian is set by the expectation value for phase fluctuations. In this case the visibility of interference contrast from a crystalline sample with lattice parameter a is limited by a Rayleigh-like transfer factor P(ls, a) in the self-coherently illuminated sample area. The model is verified by energy-filtered HRTEM images of hexagonal BN and identifies energy-loss-induced phase noise as a single-electron visibility limit distinct from resolution limitations caused by ensemble-coherence or counting-statistical noise.

cond-mat.mtrl-sci↗

arXiv2025

Thermal and Size Effects in Ferroelastic Domains by Machine Learning

Ferroelastic domain walls (DWs) underpin key functionalities in complex oxides. In free-standing ferroic thin films, where elastic interactions are highly thickness dependent, understanding DW behaviour across length scales and external stimuli is crucial. A thickness-dependent monopolar-to-dipolar crossover in elastic DW behaviour has been reported; however, how temperature influences this regime remains unexplored. Here, LaAlO3 thin films spanning the dipolar ($<200$ nm) and crossover (200-300 nm) regimes are investigated using in situ heating scanning transmission electron microscopy (STEM) and a machine-learning-driven image analysis approach. By tracking DW curvature and density from above $T_C$ (approximately $550,^\circ$C) to room temperature (RT), a distinct interplay between temperature and thickness is identified. In the dipolar regime, DWs are mobile and curved near $T_C$ and gradually freeze upon cooling, consistent with the well-known temperature freezing regime. In contrast, within the crossover regime, DWs are nearly static, with minimal reconfiguration through cooling and curvature an order of magnitude lower at RT. These results map the evolution of DWs across the thermally driven super-elastic to freezing regimes, revealing how thickness and temperature govern DW morphology and dynamics, and providing insight relevant for domain engineering in free-standing oxide thin films.

cond-mat.mtrl-sci↗

arXiv2025

Zeolitic imidazolate framework glasses emit white light

Zeolitic imidazolate framework (ZIF) glasses represent a newly emerged class of melt-quenched glasses, characterized by their intrinsic nanoporous structure, good processability, and multifunctionalities such as gas separation and energy storage. However, creating photonic functionalities in Zn-based ZIF glasses remains elusive. Here we show a remarkable broadband white light-emitting behavior in a Zn-based ZIF glass, which can be enhanced by annealing. Furthermore, we discovered a sharp red shift upon increasing annealing temperature above the critical temperature of 1.07Tg, where Tg is the glass transition temperature, for a short duration of 30 min. Finally, we achieved a high absolute internal photoluminescence quantum yield of 12.2% upon annealing of ZIF glass at 1.13Tg. Based on the optimally annealed ZIF glass, we fabricated a white light-emitting diode (LED) with the luminous efficacy of 4.2 lm/W and high operational stability, retaining 74.1% of its initial luminous efficacy after 180 min of continuous operation. These results not only demonstrate the feasibility of utilizing ZIF glasses in LED applications but also mark a significant advancement in the development of durable, efficient, and multifunctional photonic materials.

physics.optics↗

arXiv2022

Direct evidence of a continuous transition between waves and particles

The correlation between particle and wave descriptions of electron-matter interactions is analyzed by measuring the delocalization of an evanescent field using electron microscopy. Its spatial extension coincides with the energy-dependent, self-coherence length of propagating wave packets that obey the time-dependent Schrödinger equation and undergo a Goos-Hänchen shift. In the Heisenberg limit they are created by self-interferences during coherent-inelastic Coulomb interactions with a decoherence phase Δϕ = 0.5 rad and shrink to particle-like dimensions for energy losses of more than 1000 eV.

quant-ph↗