CA23136

Magnetism and chirality: twisting spins, light, and lattices for faster-than-ever spintronics

Principal investigator

THz Excitation of Circularly Polarized Raman-Active Phonons in LaAlO₃

In collaboration with the THz free electron laser facility TELBE at the Helmholtz Zentrum Dresden-Rossendorf and ETH Zürich, researcher Fabian Graf conducted a short-term scientific mission, supervised by Steven L. Johnson and Martina Basini.

The mission focused on participating in a beamtime experiment aimed at the THz pumping and detection of circularly polarized Raman-active phonons in LaAlO₃.


Experiment Highlights

  • A circularly polarized THz electric field was used to excite specific Raman-active phonon modes.
  • The experiment was designed to investigate ultrafast lattice dynamics and the potential for light-driven control of phonon states in complex oxides.

A schematic of the circularly polarized THz field used in the experiment is shown in the figure.

Towards Spin Wave Spectroscopy in Altermagnets and Antiferromagnets

This research project aims to advance the understanding and experimental exploration of spin wave phenomena in altermagnets and antiferromagnets. By leveraging cutting-edge spectroscopy techniques, we seek to investigate spin dynamics and magnon-phonon interactions in novel magnetic materials.

Collaboration

This project is a joint effort between:

  • Institute of Physics, Czech Academy of Sciences
    Supervisor: Helena Reichlová

  • University of Konstanz
    Supervisor: Sebastian Goennenwein

 
  • Research Highlights

     

    • Development and Optimization of a Spin Wave Spectroscopy Setup
      A new experimental setup for spin wave spectroscopy has been successfully implemented and optimized at the University of Konstanz, enabling high-precision measurements of spin dynamics.

    • Magnon-Phonon Coupling in YIG
      Experimental measurements of magnon-phonon coupling in yttrium iron garnet (YIG) have been conducted, focusing on the interaction mechanisms affecting propagating spin waves.

Power dissipation in altermagnetic MnTe-based Hall device

This project consists in implementing a power dissipation experiment to the study of an altermagnetic MnTe-based Hall cross. Through this work, we aimed at bringing confirmation to theoretical predictions regarding the dissipation of currents generated by Hall effects, while also investigating new ways of characterizing altermagnetic materials.

This project is a colloration between Laboratoire des Solides Irradiés, Ecole Polytechnique (Valentin Desbuis) and Institute of Physics, Czech Academy of Sciences (Dominik Kriegner).

A schematic of the electrical configuration : A load charge is connected on the transverse contact to investigate the dissipation occuring in the system.

Phonon Generation through Magnetoelastic Coupling

In collaboration with the gruop Nanoscaled Magnonic Hybrids at Rheinland-Pfälzische Technische Universität (RPTU) in Kaiserslautern, we investigated the generation of acoustic phonons via magnetoelastic coupling by applying a radio frequency (RF) field to patterned magnetic structures. Using Brillouin Light Scattering (BLS) spectroscopy, the interaction between the magnetization dynamics and the substrate’s elastic modes is analyzed to explore energy transfer mechanisms.

 

Research Highlights

Beyond demonstrating a proof of concept for magnetoelastic phonon generation, the study identifies critical factors influencing the efficiency of this process, including the relevant excitation frequency range, the external magnetic field conditions, and the geometric characteristics of the excitation structures. These insights lay the groundwork for future development of hybrid platforms that integrate phononic and spintronic functionalities for advanced signal processing applications.
 
In the photo, a Brillouin Light Scattering (BLS) setup. Taken from https://pirro.physik.rptu.de

Exploring Magnetic Topological Insulators Through Advanced Spectroscopy Techniques

This Short-Term Scientific Mission (STSM) focuses on unraveling the structural and electronic properties of magnetically doped and intrinsically nonmagnetic ternary van der Waals (vdW) compounds.

Collaboration

This project is a joint effort between:

  • University of Calabria, Italy
    Supervisor: Prof. Marco Papagno
  • Baku State University, Azerbaijan
    Supervisor: Prof. Ziya Aliev
  •  

Research Highlights

Surface and Electronic Structure Analysis

The mission began with spectroscopic investigation of doped and undoped vdW materials. X-ray Photoelectron Spectroscopy (XPS) was used to identify chemical environments and oxidation states, while Angle-Resolved Photoemission Spectroscopy (ARPES) provided insights into changes in electronic band structure.
 
Impact of Magnetic Dopants
The study focused on how magnetic doping induces structural distortions and influences topological surface states, including potential gap openings, an essential feature in realizing magnetic topological phases.
 
Scientific Impact
The findings support ongoing research into quantum materials with potential applications in spintronics, topological quantum computing, and energy conversion. The mission also strengthens international collaboration in the field of vdW-based topological materials, paving the way for joint future studies.

Exploring Non-Linear Transport in ScFe₄Al₈ for Spintronic Applications

This research project is part of the exploration of non-centrosymmetric materials for spintronics. The compound ScFe₄Al₈, recently identified as a promising candidate, has structural and magnetic properties that could generate non-linear transport effects. The aim is to assess its potential for future electronic devices exploiting broken symmetry.

Collaboration

  • Institute of Physics, Czech Academy of Sciences
    Supervisors: Helena Reichlová, Daniel Scheffler
  • IFW of Dresden (measurements campaign)
  •  

Research Highlights

Analysis of the current–voltage curves obtained on samples with a thin film of ScFe₄Al₈ reveals weak but detectable non-linear contributions for intermediate experimental conditions of temperature and applied magnetic field. These signatures, extracted using the delta method, translate into variations in slope depending on the magnetic field. Although still to be confirmed, these results constitute an initial indication consistent with the expected behaviour for non-centrosymmetric materials.

Transverse IV curves at 200 K on ScFe₄Al₈ thin film showing subtle non-linear behavior with slope variations under different magnetic fields.

Uranium based altermagnet candidates: UNiGa and UCr2Si2C

As part of the search for altermagnetic materials, two uranium based materials are selected: UNiGa and UCr2Si2C. This STSM focused on synthesizing phase pure UNiGa and UCr2Si2C samples and single crystals of UCr2Si2C that is large enough for single crystal physical property measurements.

Collaboration

This project is a joint effort between:

  • MPI for Chemical Physics of Solids

Supervisor: Dr. Eteri Svanidze

  • Koç University
    Supervisor: Assoc. Prof. Umut Aydemir

Research Highlights

    • Synthesis of UCr2Si2C

Arc melting is successfully performed to obtain UCr2Si2C without the need for 30 day annealing process.

    • Single crystal UCr2Si2C

A single crystal of size 1400 um x 170 um is separated from the arc melted button. Composition of single crystal is confirmed by EDX analysis as UCr2Si2C, which can be used for various measurements such as resistivity, Hall effect, heat capacity, and strain.

Ultrafast phononic control of spins in van der Waals multiferroic CuCrP2S6

Supported by the COST program, the investigation of the research teams led by Dr. Wenjing Yan at the University of Nottingham and Dr Alexey V. Scherbakov at Technique Universität Dortmund explored a new area of research: the interaction between magnons and phonons in a 2D van der Waals (2D-vdW) multiferroic materials. In addition to multiferroicity, such materials present distinct advantages since their electronic, optical, and symmetry characteristics can be further engineered through  “Lego-type” stacking of atomic layers.

Research Highlights:

During this short-term mission of Dr. Yan to TU Dortmund, the researchers performed magneto-optical pump-probe  experiments on hybrid phononic nanostructures based on multiferroic CuCrP2S6  (CCPS) compound, which were specifically engineered to excite different phonon modes. Results from temperature- and magnetic-field-dependent measurements indicated desirable magnon-phonon coupling in CCPS. These insights suggest promising avenues for future research on the coherent phononic control of magnetism in 2D systems.

Spin-Lattice Coupling in Ti-Doped GdMnO3 Single Crystals

In collaboration with the Institute of Physics of Advanced Materials, Nanotechnology and Photonics (IFIMUP), University of Porto, researcher Muhammad Faisal Ashraf conducted a Short-Term Scientific Mission (STSM) under the framework of COST Action CA23136 (CHIROMAG), supervised by Prof. Agostinho Moreira. The mission focused on investigating spin-lattice interactions in Ti-doped GdMnO3 single crystals using temperature-dependent Raman spectroscopy. The aim was to investigate how magnetic order affects lattice vibrations and how chemical substitution modifies spin-lattice coupling in multiferroic manganites.

Research Highlights:

During this STSM, Raman spectra were recorded from 10 K to 300 K, tracking the symmetrical stretching phonon mode near magnetic transition regions. The deviation of the phonon wavenumber from the thermal expansion fit (dashed curve) is associated with spin-lattice coupling dominated by ferromagnetic interactions and is stronger in the Ti-doped sample than in the undoped crystal, even though the Néel temperature (TN) decreases because Ti is non-magnetic. These observations provide direct experimental evidence of spin-phonon coupling and offer new insight into how lattice vibrations interact with magnetic order in multiferroic complex oxides.

Temperature dependence of the symmetrical stretching phonon mode, showing deviation from thermal expansion behavior.

Skyrmions in 3D Nanostructures

During a Short-Term Scientific Mission (STSM) within COST Action CHIROMAG (CA23136), Dr. Alberto Anadón Barcelona carried out a research stay at TU Wien, hosted by Amalio Fernández-Pacheco.

The mission focused on the fabrication and magneto-optical characterization of perpendicularly magnetized multilayers integrated onto 3D nanostructures. Multilayer stacks were optimized using magnetron sputtering and conformally deposited onto 3D FEBID nano-scaffolds previously fabricated at INMA-CSIC.

Research Highlights:

  • Growth of PMA multilayers on 3D scaffolds
    Successful deposition of multilayers with strong perpendicular magnetic anisotropy onto non-planar FEBID structures, ensuring uniform coating and structural integrity.
  • Optical access to 3D magnetic textures
    Magneto-optical Kerr effect (MOKE) and dark-field MOKE measurements revealed clear magnetic domain signatures on the curved 3D structures, demonstrating their suitability for optical probing.

Imaging of chiral magnetic states formed on curvilinear surfaces

Takeaki Gokita conducted a Short-Term Scientific Mission (STSM) within the framework of COST Action CHIROMAG (CA23136) at the Max Planck Institute for Chemical Physics of Solids, hosted by Dr. Claire Donnelly.

 

This STSM focused on imaging magnetic states deposited on curved surfaces using magnetic force microscopy (MFM) and nitrogen-vacancy magnetometry to investigate how curvature influences magnetic properties.

 

Research Highlights:

Observation of circular magnetic objects on curved surfaces

We observed circular magnetic objects in [Pt/Co] multilayers formed on curved surfaces using MFM. The local magnetic fields generated by the MFM tip may contribute to the stabilization of these circular magnetic objects.

 

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