Terahertz Magnetic and Lattice Excitations in van der Waals Ferromagnet VI3

• Published in: The journal of physical chemistry letters 2022-12, Vol.13 (48), p.11095-11104
• Main Authors: Hovančík, Dávid, Repček, Dalibor, Borodavka, Fedir, Kadlec, Christelle, Carva, Karel, Doležal, Petr, Kratochvílová, Marie, Kužel, Petr, Kamba, Stanislav, Sechovský, Vladimír, Pospíšil, Jiří
• Format: Article
• Language: English
• Subjects: Physical Insights into Materials and Molecular Properties
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.2c02944

We use the synergy of infrared, terahertz, and Raman spectroscopies with DFT calculations to shed light on the magnetic and lattice properties of VI3. The structural transition at T S1 = 79 K is accompanied by a large splitting of polar phonon modes. Below T S1, 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 T C = 50 K, two Raman modes simultaneously appear and show dramatic softening in the narrow interval around the temperature T S2 of the second structural transition associated with the order–order magnetic phase transition. Below T S2, a magnon in the THz range appears in Raman spectra. The THz magnon observed in VI3 indicates the application potential of 2D van der Waals ferromagnets in ultrafast THz spintronics, which has previously been considered the exclusive domain of antiferromagnets.