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Wydarzenia



Seminarium Oddziału Badań Magnetyków

14:00 Wednesday, 08-05-24
Microsoft Teams

Peculiar properties of van der Waals ferromagnet VI3

dr Jiří Pospíšil

Wydział Matematyki i Fizyki Uniwersytetu Karola w Pradze w Czechach

Seminarium odbędzie się zdalnie w aplikacji Microsoft Teams. W celu wzięcia udziału w wydarzeniu należy dołączyć do zespołu Seminarium OBM. Można do niego dołączyć na stałe przy użyciu kodu dostępu ol7omod (dotyczy to osób posiadających konto w domenie intibs.pl, pozostałe osoby proszę o kontakt z prof. dr. hab. Adamem Pikulem, prof. INTiBS PAN ())

The seminar will be held remotely via the Microsoft Teams application. In order to participate in the event, you must join the Seminarium OBM team. You can join it permanently using the access code ol7omod (this applies to people with an account in the intibs.pl domain, other people please contact Prof. Adam Pikul , Prof. INTiBS PAN ())

Abstract:

Transition-metal trihalides CrX3 and VX3 are fascinating van der Waals (vdW) materials that exhibit magnetic ordering even in the single-layer limit. Our present research is focused on vanadium compounds VCl3, VBr3, and VI3, which we study by measuring specific heat, magnetization, XMCD, Raman, THz, and IR spectroscopies, X-ray diffraction and all experiments supported by theoretical ab-initio calculations.
The seminar will primarily focus on our results obtained studying the vdW ferromagnet VI3. This compound is exceptional by structural trimorphism, two canted ferromagnetic phases, temperature, magnetic field, and pressure dependences of structural and magnetic phase transitions 1, 2. The unique magnetic anisotropy is characteristic of the easy magnetization axis tilted by  50° from the ab-plane3.
The most prominent property of VI3 is the significant unquenched orbital moment of the V3+ ion theoretically predicted4 and experimentally proven by XMCD measurements5. The ferromagnetic ground state of VI3 is characterized by two inequivalent V-sites. Our ligand field multiplet simulations of XMCD spectra in synergy with the results of DFT calculations agree with the existence of two V sites with different orbital occupations and, therefore, different orbital moment magnitudes in the ground state5.
The strong magnetoelastic coupling is manifested by the results of complementary spectroscopic measurements (Raman, THz, and IR) supported by theoretically calculated phonon modes. Below Curie temperature, two Raman modes simultaneously appear and show dramatic softening in the narrow temperature interval around the second structural transition associated with the order−order magnetic phase transition. In the ground state phase, 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 been considered the exclusive domain of antiferromagnets 6.


1. P. Doležal, et al., Physical Review Materials 3 , 121401(R) (
2. J. Valenta, et al., Physical Review Materials 103 , 054424 (
3. A. Koriki, et al., Physical Review B 103 , 174401 (
4. L. M. Sandratskii and K. Carva, Physical Review B 103 , 214451 (
5. D. Hovančík, et al., Nano Letters 23 , 1175−1180 (
6. D. Hovančík, et al., The Journal of Physical Chemistry Letters 13 , 11095 (

INSTYTUT NISKICH TEMPERATUR
I BADAŃ STRUKTURALNYCH
im. Włodzimierza Trzebiatowskiego
POLSKIEJ AKADEMII NAUK
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