IMF 2023

Spectroscopic studies of low frequency magnetic and lattice excitations in van der Waals ferromagnet VI3

Fedir Borodavka 1 Dávid Hovančík 2 Dalibor Repček 1,3 Stanislav Kamba 1
1Institute of Physics, Department of Dielectrics, Czech Academy of Sciences, Prague, Czech Republic
2Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
3Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic

Magnetic van der Waals (vdW) materials have become a target of intense basic and applied research due to the high potential for microelectronics and spintronics. Raman scattering has proven to be an effective tool for investigating the magnetic and lattice degrees of freedom in 2D magnets [1].

In this contribution, the complementarity of infrared (IR), terahertz (THz) and Raman spectroscopies was used to study the structural and magnetic phase transitions in bulk VI3 single crystal at temperatures down to 4 K. Below the structural phase transition at TS1 = 79 K, similar as for the exfoliated flakes of VI3 [2], a large splitting of polar phonon modes appears and strong ferromagnetic fluctuations are observed. The variations of phonon frequencies at 55 K, induced by magnetoelastic coupling enhanced by spin-orbit interaction, indicate the proximity of long-range ferromagnetic order. Below TC = 50 K, two Raman modes simultaneously appear and show a giant softening in the narrow interval around the temperature TS2 of the second structural transition. Below TS2, a magnon in the low frequency range comes out in the Raman spectra. This THz magnon, observed in bulk VI3, indicates the application potential of 2D van der Waals ferromagnets in ultrafast THz spintronics.

Polarized Raman spectra of VI3 taken at 300 K in the rhombohedral phase and at 4 K in the FM triclinic phase.

Figure 1. Polarized Raman spectra of VI3 taken at 300 K in the rhombohedral phase and at 4 K in the FM triclinic phase.

The work was supported by Operational Programme: Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project No. SOLID21 – CZ.02.1.01/0.0/0.0/16_019/0000760)


[1] Kim K., Lee J. U., Cheong H. Raman spectroscopy of two-dimensional magnetic van der Waals materials. Nanotechnology 2019, 30 (45), 10, Review
[2] Lyu B. et al. Probing the ferromagnetism and spin wave gap in VI3 by helicity-resolved Raman spectroscopy. Nano Letters 2020, 20 (8), 6024-6031





IMF 2023




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