FHI Poster Sessions

Session

PC Department

28 Apr 2022, 14:00

At FHI (Dahlem) and IRIS (Adlershof)

Conveners

PC Department: PC Poster Session

• Carsten Baldauf (Fritz-Haber-Institut der MPG)

69. Comparison of electron analyzers for time-resolved ARPES experiments

Mr Julian Maklar (FHI)

PC

For angle-resolved photoelectron spectroscopy (ARPES), an important element is the employed electron analyzer. While hemispherical analyzers with angle-dispersing electron lenses have been the working horse for decades, recently time-of-flight based momentum microscopes have shown a huge improvement in parallel detection efficiency, allowing for simultaneous detection of multiple Brillouin...

67. Concept for Open Data and Transparent Data Analytics in Multi-Dimensional Photoemission Spectroscopy

Dr Tommaso Pincelli (FHI)

PC

The complexity and size of photoemission data is rapidly increasing as new technological breakthroughs have enabled multidimensional parallel acquisition of multiple observables. Most of the community is currently using heterogeneous data formats and workflows.
We propose a new data format based on NeXus [1] a hierarchically organized hdf5 structure. The aim is to immediately enable...

64. Dynamic Screening of Quasiparticles in WS2 Monolayers en route to Ultrafast Phenomena at TMDC/Organic Hybrid Interfaces

Mr Stefano Calati (FHI)

PC

The low dimensional nature of transition metal dichalcogenides (TMDCs) and the resulting reduced screening significantly influence their non-equilibrium optical properties, as dynamic screening by photoexcited quasiparticles governs the transient response. In this work, we investigate the role of different photoexcited quasiparticles on the dynamic response of WS2 monolayers. Firstly, we...

65. Electron and Exciton Dynamics in Low-Dimensional Materials and Heterostructures

Mr Alexander Neef (FHI)

PC

The extreme versatility of low-dimensional systems and their combinations in heterostructures offers access to emergent properties and processes, especially in light-matter interaction. A proper understanding of the underlying physics requires techniques that sample the electronic structure, i.e. crystal momentum and binding energy, at different times after an initial excitation. The...

73. Hyperbolic Shear Polaritons in Low-Symmetry Crystals

Dr Nikolai C. Paßler (FHI)

PC

The lattice symmetry of a crystal is one of the most important factors in determining its optical properties. Particularly, low-symmetry crystals offer powerful opportunities to control light propagation, polarization and phase1. Materials featuring extreme optical anisotropy can support a hyperbolic response, enabling coupled light-matter interactions, also known as polaritons, with highly...

75. MIR Time-Domain Ellipsometry via 2D Electrooptic Sampling

Mrs Leona Nest (FHI)

PC

Terahertz time-domain spectroscopy (THz-TDS) has been established as a powerful tool for both industrial material inspection and fundamental material science. The latter strongly benefits from measuring conductivities, dielectric functions, and related phase transitions in e.g. semiconductors, topological insulators, high-temperature superconductors, and 2D materials. Moreover, THz-TDS is well...

70. Nonlinear Vibrational Interface Spectroscopy with Nanometer Depth Resolution: The SFG/DFG Method

Mr Álvaro Díaz Duque (FHI)

PC

The unique physical and chemical properties of interfaces are governed by a finite depth that describes the transition from the topmost atomic layer to the properties of the bulk material. Understanding the physical nature of interfaces thus requires detailed insight into the different structures, chemical compositions, and physical processes that form this interfacial region. Such insight has...

71. Phase-Resolved, Wide-Field Sum Frequency Generation Microscopy

Mr Ben John (FHI)

PC

Molecular specific imaging on surfaces or interfaces is crucial for understanding the structures and dynamics of many inhomogeneous systems in various fields such as biology, heterogeneous catalysis etc. A key role among the various microscopy techniques plays vibrational sum frequency generation (VSFG) microscopy due to its intrinsic sensitivity to broken centro-symmetry and its ability to...

72. Super-resolution widefield microscopy using infrared-visible sum-frequency generation

Mrs Richarda Niemann (FHI)

PC

Nonlinear optical imaging with a spatial resolution well below the Abbe diffraction limit of light, such as stimulated emission depletion (STED) microscopy, has enabled many ground-breaking discoveries. In the infrared spectral range, however, no comparable schemes exist, and high-resolution infrared imaging has so far been restricted to scanning probe techniques such as scattering near-field...

80. Terahertz-field-driven Spin Dynamics in (Anti-)Ferromagnets

Dr Alexander Chekhov (FHI)

PC

To push writing of magnetic information to ultrafast time scales, it is essential to understand the response of a magnetically ordered solid to an instantaneous perturbation. A model experiment in the case of a ferromagnet (such as Fe) is an excitation by a femtosecond laser pulse. The resulting magnetization quenching is known to proceed on a surprisingly fast time scale of 100 fs, and this...

78. Towards Atomic-Scale Scanning Near-Field Optical Microscopy

Dr Melanie Müller (FHI)

PC

Scattering-type scanning near-field optical microscopy (s-SNOM) allows imaging and spectroscopy far below the diffraction limit by the nanoscopically-confined optical fields in the vicinity of sharp metal tips. Standard s-SNOM is based on tapping-mode atomic-force microscopy (AFM), with background-free detection of the local optical signal achieved by high-harmonic demodulation and...

76. Tracing ultrafast hot electron and coherent phonon dynamics with time-resolved STM

Dr Melanie Müller (FHI)

PC

The ultrafast dynamics of electrons and phonons in solid state matter can be of crucial importance for a variety of fundamental processes such as chemical reactions and ultrafast phase transitions. Tracing the ultrafast relaxation out of equilibrium after impulsive optical excitation provides valuable insight into microscopic coupling mechanisms and energy transfer processes. Whereas...

68. Tracking Ultrafast Charge-Density-Wave Dynamics with Multidimensional Photoemission Spectroscopy

Mr Julian Maklar (FHI)

PC

The interaction of complex solids with intense light pulses can induce novel emergent phenomena far from equilibrium. Prominent examples include optical enhancement of the critical temperature in certain superconductors and photo-stabilization of metastable states. A common theme in materials featuring exotic out-of-equilibrium behavior is the formation of charge density waves (CDWs), i.e., a...

74. Ultrafast Polarization Responses of Lead Halide Perovskites

Mr Maximilian Frenzel (FHI)

PC

Over the last decade, lead halide perovskite (LHP) semiconductors have emerged as a promising material for optoelectronic devices such as solar cells or LEDs. These materials show a range of outstanding optoelectronic properties including long charge carrier diffusion lengths and apparent defect tolerance. However, the microscopic origin of these properties remains under debate. It has been...

79. Ultrafast Spin Transport in Magnetic Heterostructures: from Varying Conductivity to an Electro-Optic Terahertz Analyzer

Mr Oliver Gückstock (FHI)

PC

Transport of spin angular momentum and the conversion of the resulting spin current to a charge current are fundamental operations required for future spin-electronic devices. To be competitive and compatible with other information carriers such as light, it is required to push the bandwidth of these operations to the terahertz (THz) frequency range.
Here, we use femtosecond laser pulses...

66. Ultrafast Structural Dynamics of Solids Investigated with Femtosecond Electron Diffraction

Dr Hélène Seiler (FHI)

PC

Femtosecond electron diffraction (FED) enables the direct observation of the crystal lattice’s response to laser excitation. It is therefore ideally suited to study the ultrafast energy flow from electrons to phonons as well as other photo-induced changes of the lattice, such as structural phase transitions, coherent phonons, and lattice distortions.
We have employed FED to probe the nuclear...

77. Ultrasensitive Raman Spectroscopy in Atomic-Scale Plasmonic Cavities

Dr Borja Cirera (FHI)

PC

Recently, ultrasensitive and ultrahigh resolution optical spectroscopy has been demonstrated using low-temperature tip-enhanced Raman and photoluminescence spectroscopy (TERS/TEPLS) with sub-molecular resolution [1-3]. The exceptional sensitivity and the spatial resolution rely on atomically-confined electromagnetic fields in (sub-)nanoscale gaps. Our approach, with simultaneous access to...