M.Sc. Sreedevi Janardhanan

M.Sc. Sreedevi Janardhanan

Department of Nanostructures Physics

Tel: +48 881 350 140
Loc: wing G, first floor, room 180
Email: srejan@amu.edu.pl

Research interests

Keywords: Magnonics, Spinwaves, PMA, BLS

Working project:

Reconfigurable Topological properties and frustrated ground states in magnonics

Description of project :

the emerging research and technology field focused on study of spin waves which can transfer a spin for large distance without charge transfer, what minimizes the energy cost of the logic operations. Magnonic devices are easily reconfigurable and favorable for active control, difficult to achieve for other devices from photonics or electronics.

The main objective of the project is to define the MC based on thin PMA multilayers with an array of antidots possessing multiple magnetization states in the rims around antidots, suitable for formation of the confined and propagating SWs with nontrivial topological properties. we aim to demonstrate numerically and validate experimentally three breakthrough ideas providing new physics in magnonics and wave phenomena in general, and opening the rout for applications.

Publications

2024
4.	Sreedevi Janardhanan, Maciej Krawczyk, Aleksandra Trzaskowska Spin-Wave Dynamics in Ultra-thin Ferromagnetic Films, Patterned, and Non-patterned Bandyopadhyay, Supriyo, Barman, Anjan (Ed.): Nanomagnets as Dynamical Systems: Physics and Applications, pp. 33–69, Springer Nature Switzerland, Cham, 2024, ISBN: 978-3-031-73191-4. Abstract \| Links \| BibTeX @inbook{Janardhanan2024b, title = {Spin-Wave Dynamics in Ultra-thin Ferromagnetic Films, Patterned, and Non-patterned}, author = {Sreedevi Janardhanan and Maciej Krawczyk and Aleksandra Trzaskowska}, editor = {Supriyo Bandyopadhyay and Anjan Barman}, url = {https://doi.org/10.1007/978-3-031-73191-4_2}, doi = {10.1007/978-3-031-73191-4_2}, isbn = {978-3-031-73191-4}, year = {2024}, date = {2024-11-10}, booktitle = {Nanomagnets as Dynamical Systems: Physics and Applications}, pages = {33--69}, publisher = {Springer Nature Switzerland}, address = {Cham}, abstract = {Exploring spin-waveSpin wave (SW) dynamics opens new avenues for technological applications across various fields. This chapter provides a comprehensive review of spin-waveSpin wave (SW) dynamics in both patterned and non-patterned ferromagnetic thin films, and emphasizes the significance of perpendicular magnetic anisotropyPerpendicular magnetic anisotropy (PMA) in this context as well. The chapter begins with an overview of the basic concept and relevance of spin wavesSpin wave (SW), followed by a detailed discussion of Brillouin light scatteringBrillouin light scattering (BLS) methodology. We explore the unique properties of spin wavesSpin wave (SW) in patterned films, such as magnonic crystalsMagnonic crystals (MC), and a comparative study with the behaviour in continuous films has been presented in detail. The future perspective from technological point of view of spin-wave research is vast, ranging from high-frequency data transmission to quantum information processing. Here we highlighted applications encompass spin-wave logic devices, magnonic waveguide, quantum computingSpin wave computing, and the role of spin wavesSpin wave (SW) in the development of novel materials with tailored magnetic properties. Finally, this review addresses the challenges associated with achieving precise control over spin-waveSpin wave (SW) propagation, elucidating spin-waveSpin wave (SW) interactions at the nanoscale, and integrating spin-waveSpin wave (SW) technology with existing technological frameworks.}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } Close Exploring spin-waveSpin wave (SW) dynamics opens new avenues for technological applications across various fields. This chapter provides a comprehensive review of spin-waveSpin wave (SW) dynamics in both patterned and non-patterned ferromagnetic thin films, and emphasizes the significance of perpendicular magnetic anisotropyPerpendicular magnetic anisotropy (PMA) in this context as well. The chapter begins with an overview of the basic concept and relevance of spin wavesSpin wave (SW), followed by a detailed discussion of Brillouin light scatteringBrillouin light scattering (BLS) methodology. We explore the unique properties of spin wavesSpin wave (SW) in patterned films, such as magnonic crystalsMagnonic crystals (MC), and a comparative study with the behaviour in continuous films has been presented in detail. The future perspective from technological point of view of spin-wave research is vast, ranging from high-frequency data transmission to quantum information processing. Here we highlighted applications encompass spin-wave logic devices, magnonic waveguide, quantum computingSpin wave computing, and the role of spin wavesSpin wave (SW) in the development of novel materials with tailored magnetic properties. Finally, this review addresses the challenges associated with achieving precise control over spin-waveSpin wave (SW) propagation, elucidating spin-waveSpin wave (SW) interactions at the nanoscale, and integrating spin-waveSpin wave (SW) technology with existing technological frameworks. Close https://doi.org/10.1007/978-3-031-73191-4_2 doi:10.1007/978-3-031-73191-4_2 Close
3.	Sreedevi Janardhanan, Sławomir Mielcarek, Hubert Głowiński, Daniel Kiphart, Piotr Kuświk, Aleksandra Trzaskowska Spin wave dynamics in CoFeB bilayers with wedged Au spacer Journal of Magnetism and Magnetic Materials, 589 , pp. 171570, 2024, ISSN: 0304-8853. Abstract \| Links \| BibTeX @article{JANARDHANAN2024171570, title = {Spin wave dynamics in CoFeB bilayers with wedged Au spacer}, author = {Sreedevi Janardhanan and Sławomir Mielcarek and Hubert Głowiński and Daniel Kiphart and Piotr Kuświk and Aleksandra Trzaskowska}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323012209}, doi = {https://doi.org/10.1016/j.jmmm.2023.171570}, issn = {0304-8853}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = {171570}, abstract = {This paper presents the experimental studies of ferromagnetic layers separated by a heavy metal wedge. The studied system consists of two thin layers of CoFeB separated by a wedged Au spacer. By performing Brillouin light scattering measurements of the spin-wave dispersion relations, and dependences on the magnetic field, we extract magnetic parameters in the studied ferromagnetic layers as a function of heavy metal thickness. We concluded that for thin ferromagnetic double layers, the magnetic properties strongly depend on the thickness of the wedge gold layer spacer. In particular, the presence of perpendicular magnetic anisotropy diminishes as the thickness of the magnetic material is increased, and at the spacers thicker than 2.5 nm the dynamic coupling between propagating spin waves in both layers is negligible. These findings have potential advantages for the development of future spintronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close This paper presents the experimental studies of ferromagnetic layers separated by a heavy metal wedge. The studied system consists of two thin layers of CoFeB separated by a wedged Au spacer. By performing Brillouin light scattering measurements of the spin-wave dispersion relations, and dependences on the magnetic field, we extract magnetic parameters in the studied ferromagnetic layers as a function of heavy metal thickness. We concluded that for thin ferromagnetic double layers, the magnetic properties strongly depend on the thickness of the wedge gold layer spacer. In particular, the presence of perpendicular magnetic anisotropy diminishes as the thickness of the magnetic material is increased, and at the spacers thicker than 2.5 nm the dynamic coupling between propagating spin waves in both layers is negligible. These findings have potential advantages for the development of future spintronic devices. Close https://www.sciencedirect.com/science/article/pii/S0304885323012209 doi:https://doi.org/10.1016/j.jmmm.2023.171570 Close
2023
2.	Sreedevi Janardhanan, Sławomir Mielcarek, Hubert Głowiński, Mateusz Kowacz, Piotr Kuświk, Maciej Krawczyk, Aleksandra Trzaskowska Investigation of spin wave dynamics in Au/CoFeB/Au multilayers with perpendicular magnetic anisotropy Scientific Reports, 13 (1), pp. 22494, 2023, ISSN: 2045-2322. Abstract \| Links \| BibTeX @article{Janardhanan2023b, title = {Investigation of spin wave dynamics in Au/CoFeB/Au multilayers with perpendicular magnetic anisotropy}, author = {Sreedevi Janardhanan and Sławomir Mielcarek and Hubert G{ł}owi{ń}ski and Mateusz Kowacz and Piotr Ku{ś}wik and Maciej Krawczyk and Aleksandra Trzaskowska}, url = {https://doi.org/10.1038/s41598-023-49859-8}, doi = {10.1038/s41598-023-49859-8}, issn = {2045-2322}, year = {2023}, date = {2023-12-15}, journal = {Scientific Reports}, volume = {13}, number = {1}, pages = {22494}, abstract = {We have carried out an experimental investigation of the spin-wave dynamics in the Au/CoFeB/Au multilayer consisting of a ferromagnetic film with thicknesses of 0.8, 0.9 and 1.0 nm. We employed the Brillouin light scattering spectroscopy to measure the frequency of the spin waves in dependence on the wave vector. Additionally, we characterized the samples by ferromagnetic resonance measurements. We found that the considered samples exhibit perpendicular magnetic anisotropy with low damping, indicating small pumping effects. Furthermore, we found a nonreciprocal dispersion relation pointing at a non-negligible Dzyaloshinskii--Moriya interaction. These results make the Au/CoFeB/Au multilayer a compelling subject for further analysis and as a potential material for future applications within magnonics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We have carried out an experimental investigation of the spin-wave dynamics in the Au/CoFeB/Au multilayer consisting of a ferromagnetic film with thicknesses of 0.8, 0.9 and 1.0 nm. We employed the Brillouin light scattering spectroscopy to measure the frequency of the spin waves in dependence on the wave vector. Additionally, we characterized the samples by ferromagnetic resonance measurements. We found that the considered samples exhibit perpendicular magnetic anisotropy with low damping, indicating small pumping effects. Furthermore, we found a nonreciprocal dispersion relation pointing at a non-negligible Dzyaloshinskii--Moriya interaction. These results make the Au/CoFeB/Au multilayer a compelling subject for further analysis and as a potential material for future applications within magnonics. Close https://doi.org/10.1038/s41598-023-49859-8 doi:10.1038/s41598-023-49859-8 Close
1.	Sreedevi Janardhanan, Sławomir Mielcarek, Piotr Kuświk, Maciej Krawczyk, Aleksandra Trzaskowska High-resolution Brillouin light scattering study on Ti/Au/Co/Ni multilayer Journal of Magnetism and Magnetic Materials, 586 , pp. 171209, 2023, ISSN: 0304-8853. Abstract \| Links \| BibTeX @article{JANARDHANAN2023171209, title = {High-resolution Brillouin light scattering study on Ti/Au/Co/Ni multilayer}, author = {Sreedevi Janardhanan and Sławomir Mielcarek and Piotr Kuświk and Maciej Krawczyk and Aleksandra Trzaskowska}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323008594}, doi = {https://doi.org/10.1016/j.jmmm.2023.171209}, issn = {0304-8853}, year = {2023}, date = {2023-09-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {586}, pages = {171209}, abstract = {The topic of this paper addresses the Brillouin light scattering (BLS) study of the spin-wave and surface acoustic wave dynamics in the multilayer consisting of Ti/Au/Co/Ni deposited on Si substrate. We make the quantitative analysis of spin-wave frequency under a range of wave vectors to determine the dispersion relation and to study the effect of the magnetic field. These findings were correlated with theoretical models to determine the magnetic system parameters, such as magnetization, Lande g factor, exchange stiffness constant etc. In addition to this, we have conducted finite element method based simulations to understand the nature of surface phonons and to determine the elastic tensor parameters for the Ti/Au/Co/Ni layer from the fitting of simulation results with the experiment data points.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The topic of this paper addresses the Brillouin light scattering (BLS) study of the spin-wave and surface acoustic wave dynamics in the multilayer consisting of Ti/Au/Co/Ni deposited on Si substrate. We make the quantitative analysis of spin-wave frequency under a range of wave vectors to determine the dispersion relation and to study the effect of the magnetic field. These findings were correlated with theoretical models to determine the magnetic system parameters, such as magnetization, Lande g factor, exchange stiffness constant etc. In addition to this, we have conducted finite element method based simulations to understand the nature of surface phonons and to determine the elastic tensor parameters for the Ti/Au/Co/Ni layer from the fitting of simulation results with the experiment data points. Close https://www.sciencedirect.com/science/article/pii/S0304885323008594 doi:https://doi.org/10.1016/j.jmmm.2023.171209 Close