伟德国际_伟德国际1946$娱乐app游戏

图片

Experimental Physics II

  1. 伟德国际_伟德国际1946$娱乐app游戏
  2. Faculties
  3. Faculty of Mathematics, Natural Sciences, and Materials Engineering
  4. Institute of Physics
  5. Chairs, professors and groups
  6. Experimental Physics II
  7. Research

Research

Ultrafast Carrier Dynamics in Low Dimensional Heterostructures

?

B. Arnoldi

Ultrafast Magnetization Dynamics? ? ? ??

?

? 伟德国际_伟德国际1946$娱乐app游戏 of Augsburg

Spin Functionalities in Molecular Hybrid Structures

?

B. Arnoldi

?

Ultrafast Carrier Dynamics in Low Dimensional Heterostructures

The ultrafast dynamics of charge and spin carriers in solids plays a crucial role in many fundamental and device-relevant phenomena, ranging from light harvesting in molecular and inorganic semiconductors to spin filtering at functional interfaces. In our research, we study the essential energy and (angular) momentum dissipation process of optically excited charge and spin carriers in energy and momentum space on their intrinsic femtosecond to picosecond timescale. This will build the foundation for shaping the spin-dependent materials properties on ultrafast timescales by optical excitation. Currently, we focus on

?
  • the evolution and interconversion of charge transfer and Frenkel excitons in molecular materials
  • intersite and interlayer charge and spin transfer processes in molecular and inorganic 2D heterostructures
  • momentum dependent lifetimes of quantum-confined electrons in 2D metal-organic porous network structures

For our research, we employ time-, spin- and momentum-resolved photoemission spectroscopy and?momentum microscopy. In this pump-probe study, a first femtosecond laser pulse optically excites electrons in the excited state region, while the second probe pulse photoexcites carriers into the vacuum with a well-defined time delay, where they are detected by state-of-the-art photoemission detector systems. For molecular systems, we additionally use the framework of photoemission orbital tomography to gain insight into the spatial distribution of the emitted carriers through their characteristic spectroscopic signatures in momentum space.

Schematic illustration and example momentum microscopy data of the ultrafast carrier scattering in a material with simple parabolic bands.

?

Optical excitation of low dimensional materials can lead to the formation of various excitons ranging from charge transfer and Frenkel excitations in molecular materials to intra- and interlayer excitons in 2D heterostructures.

?

Selected Publications:

  • Revealing hidden spin polarization in centrosymmetric van der Waals materials on ultrafast timescales
    B. Arnoldi, S. L. Zachritz, S. Hedwig, M. Aeschlimann, O. L. A. Monti, and B. Stadtmüller
    Nat. Commun. 15, 3573, (2024)
  • Disentangling the multiorbital contributions of excitons by photoemission exciton tomography
    W. Bennecke, A. Windischbacher, D. Schmitt, J. P. Bange, R. Hemm, C. S. Kern, G. D’Avino, X. Blase, D. Steil, S. Steil, M. Aeschlimann, B. Stadtmüller, M. Reutzel, P. Puschnig, G. S. M. Jansen, and S. Mathias
    Nat. Commun. 15, 1804 (2024)
  • Coherent response of the electronic system driven by non-interfering laser pulses
    T. Eul, E. Prinz, M. Hartelt, B. Frisch, M. Aeschlimann, and B. Stadtmüller
    Nat. Commun. 13, 3324 (2022)
  • Time-resolved two-photon momentum microscopy—A new approach to study hot carrier lifetimes in momentum space
    F. Haag, T. Eul, P. Thielen, N. Haag, B. Stadtmüller, and M. Aeschlimann
    Review of Scientific Instruments 90, 103104 (2019)
  • Strong modification of the transport level alignment in organic materials after optical excitation
    B. Stadtmüller, S. Emmerich, D. Jungkenn, N. Haag, M. Rollinger, S. Eich, M. Maniraj, M. Aeschlimann, M. Cinchetti, and S. Mathias
    Nat. Commun. 10, 1470 (2019)

?

?

Ultrafast Magnetization Dynamics

Controlling spin states of condensed matter is a crucial prerequisite for the realization of novel information technology concepts. In our research, we lay the foundation for such efforts by focusing on the ultrafast magnetization dynamics of magnetic materials after optical excitation with femtosecond light pulses. We aim to reveal the microscopic processes governing the ultrafast magnetization dynamics and identify new ways to control the generation of spin-polarized carriers in these materials.

Currently, we focus on

  • optically induced intersite and interlayer spin transfer in ferromagnetic alloys and metal-organic hybrid structures
  • ultrafast magnetization dynamics in compensated magnets, i.e., in antiferromagnets and altermagnets

For our research, we combine time-, spin- and momentum-resolved photoemission spectroscopy with ultrafast magneto-optics experiments to obtain complementary views on the ultrafast spin-dependent material response of the magnets after optical excitation with fs-light pulses.

?

?

?

?

?

The interaction of fs light pulses with magnetic materials leads to a loss of magnetic order on sub-ps timescales. This loss of magnetic order can be monitored in real-time using magneto-optical pump-probe techniques.
Optical-induced intersite and interlayer charge transfer processes in exchange coupled metal-organic hybrid structures can lead to transient changes in the magnetic order in tailored magnetic-molecular hybrid structures, but also in magnets such as antiferro- and altermagnets [right image adapted from Phys. Rev. X 12, 040501 (2022)].

?

Selected Publications and Reprints:

  • All optical excitation of spin polarization in d-wave altermagnets
    M. Weber, S. Wust, L. Haag, A. Akashdeep, K. Leckron, C. Schmitt, R. Ramos, T. Kikkawa, E. Saitoh, M. Kl?ui, L. ?mejkal, J. Sinova, M. Aeschlimann, G. Jakob, B. Stadtmüller, H. C. Schneider
    arXiv:2408.05187; https://doi.org/10.48550/arXiv.2408.05187
  • Observation of time-reversal symmetry breaking in the band structure of altermagnetic RuO2
    O. Fedchenko, J. Minár, A. Akashdeep, S. W. D’Souza, D. Vasilyev, O. Tkach, L. Odenbreit, Q. Nguyen, D. Kutnyakhov, N. Wind, L.?Wenthaus, M. Scholz, K. Rossnagel, M. Hoesch, M. Aeschlimann, B. Stadtmüller, M. Kl?ui, G. Sch?nhense, T. Jungwirth, A.?B.?Hellenes, G. Jakob, L. ?mejkal, J. Sinova, H.-J. Elmers
    Sci. Adv. 10, eadj4883 (2024)
  • Control of transport phenomena in magnetic heterostructures by wavelength modulation
    C. Seibel, M. Weber, M. Stiehl, S. T. Weber, M. Aeschlimann, H. C. Schneider, B. Stadtmüller, B. Rethfeld
    Phys. Rev. B 106, L140405 (2022)
  • Ultrafast spin transfer in ferromagnetic alloys
    M. Hofherr, S. H?user, P. Tengdin, S. Sakshath, H. T. Nembach, S. T. Weber, J. M. Shaw, T. J. Silva, H. C. Kapteyn, M. Cinchetti, B. Rethfeld, M. M. Murnane, D. Steil, B Stadtmüller, S. Sharma, M. Aeschlimann, S. Mathias
    Sci. Adv. 6 eaay8717 (2020)
  • Band structure evolution during the ultrafast ferromagnetic-paramagnetic phase transition in cobalt
    S. Eich, M. Pl?tzing, M. Rollinger, S. Emmerich, R. Adam, C. Chen, H. C. Kapteyn, M. M. Murnane, L. Plucinski, D. Steil, B.?Stadtmüller, M. Cinchetti, M. Aeschlimann, C.?M. Schneider, S. Mathias
    Sci. Adv. 3 (3), e1602094 (2017)

?

?

Spin Functionalities in Molecular Hybrid Structures

Molecular materials on surfaces are a fascinating construction kit for controlling spin functionalities such as spin filtering and spin diffusion on the nanoscale. However, tuning such spin functionalities requires an in-depth understanding of the delicate balance of the intermolecular and molecule-surface interactions in molecular-based hybrid structures typically reflected by the arrangement of the molecular superstructures. In our research, we, therefore, focus on the link between the efficiency of spin functionalities and the structural order of molecular–surface hybrid structures. Currently, we focus on

  • chirality-induced spin filtering in chiral metal-molecular hybrid structures
  • spin-polarization of quantum confined surface electrons in tailored metal-organic networks
  • spin filtering in bare and passivated magnetic metal-molecule hybrid structures

For our investigations, we combine structural characterization tools such as scanning tunneling microscopy and the synchrotron-based normal-incidence X-ray standing waves technique with spin-resolved electron spectroscopy tools to obtain a comprehensive view of the interactions and corresponding spin functionalities in molecular hybrid structures.

?

?

The chirality-induced spin filtering or CISS effect leads to spin filtering in chiral structures without magnetic materials or large spin-orbit materials.

?

?

The structural properties of molecular hybrid structures can be controlled by external parameters such as temperature, intercalation, or light.

Selected Publications:

  • Vectorial Electron Spin Filtering by an All-Chiral 伟德国际_伟德国际1946$娱乐app游戏–Molecule Heterostructure
    C. B. Viswanatha, J. St?ckl, B. Arnoldi, S. Becker, M. Aeschlimann, B. Stadtmüller
    J. Phys. Chem. Lett. 2022, 13, 6244–6249
  • Observation of optical coherence in a disordered metal-molecule interface by coherent optical two-dimensional photoelectron spectroscopy
    M. Aeschlimann, T. Brixner, M. Cinchetti, M. Feidt, N. Haag, M. Hensen, B. Huber, T. Kenneweg, J. Kollamana, C. Kramer, W. Pfeiffer, S. Ponzoni, B. Stadtmüller, P. Thielen
    Phys. Rev. B 105, 205415 (2022)
  • Thermal-Driven formation of 2D Nanoporous Networks on 伟德国际_伟德国际1946$娱乐app游戏 Surfaces
    L. Lyu, M. Mahalingam, S. Mousavion, S. Becker, H. Huang, M. Aeschlimann, B. Stadtmüller
    J. Phys. Chem. C 123, 26263-26271 (2019)
  • Spin- and Angle-Resolved Photoemission Study of the Alq3/Co Interface
    J. St?ckl, A. Jurenkow, N. Gro?mann, M. Cinchetti, B. Stadtmüller, M. Aeschlimann
    J. Phys. Chem. C 122 (12), 6585–6592 (2018)
  • Modifying the Surface of a Rashba-Split Pb-Ag Alloy Using Tailored 伟德国际_伟德国际1946$娱乐app游戏-Organic Bonds
    B. Stadtmüller, J. Seidel, N. Haag, L. Grad, C. Tusche, G. van Straaten, M. Franke, J. Kirschner, C. Kumpf, M. Cinchetti, M. Aeschlimann
    Phys. Rev. Lett. 117, 096805 (2016)

Search