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SUMMARY:THE PRESSURE EFFECT ON CRYSTAL AND MAGNETIC STRUCTURES OF VAN DER 
 WAALS MATERIALS
DTSTART;VALUE=DATE-TIME:20220713T132000Z
DTEND;VALUE=DATE-TIME:20220713T134000Z
DTSTAMP;VALUE=DATE-TIME:20260414T123207Z
UID:indico-contribution-333@events.sinp.msu.ru
DESCRIPTION:Speakers: O.N. Lis (FLNP JINR)\nThe recent discovery of magnet
 ic ordering in van der Waals (vdW) materials down to the monolayer limit h
 as opened a new direction in the field of two-dimensional materials\, allo
 wing researchers to explore magnetism in lower dimensions in simple crysta
 l systems. The advent of long-range 2D ferromagnetism brings about new tra
 nsport phenomena in two dimensions\, like tunneling magnetoresistance and 
 electrical switching of magnetic states promoting 2D ferromagnets as versa
 tile platforms for engineering new quantum states and device functionaliti
 es. CrBr3 and Fe3GeTe2 are also one of the brightest representatives of th
 is class of materials\, which also attract the attention of researchers be
 cause of the various observed physical phenomena. The knowledge of relatio
 nship between magnetic and crystal structure of such compounds\, which can
  be obtained from high-pressure investigations\, is very essential for und
 erstanding the nature and mechanism of physical phenomena observed in it.\
 nThe present work focuses on the investigations of crystal and magnetic st
 ructures of CrBr3 and Fe3GeTe2 in wide temperature and pressure ranges. De
 tailed studies of the crystal structure of the materials were carried out 
 using neutron diffraction on a DN-6 diffractometer of a pulsed high-flux I
 BR-2 reactor (FLNP\, JINR\, Dubna\, Russia) in temperature range of 6-300 
 K and at pressure up to 5 GPa. Neutron diffraction investigations of CrBr3
  revealed to observe the formation of the long-range ferromagnetic order w
 hich leads to the negative thermal volume expansion and anomalous thermal 
 variation of interatomic distances and angles\, caused by the spin-lattice
  coupling. Related effects were found in vibrational spectra of this compo
 und. Noticeable anomalies near the Curie point are observed on the tempera
 ture dependences of Raman peak frequencies as well as on their full-width 
 at half-maximum which indicates the strong spin-phonon coupling in CrBr3. 
 The high pressure effect made it possible to identify unusual changes in t
 he diffraction spectra and changes of Raman modes\, which may be associate
 d with a phase transition in CrBr3. It was also obtained the evolution of 
 the unit cell parameters\, bond lengths under high pressure. The X-ray dif
 fraction of Fe3GeTe2 at high pressure revealed anomalies on the baric beha
 vior of structural parameters without clearable structural transition with
  changing the symmetry. The vanishing of the vibrational modes of Fe3GeTe2
  at high pressures and low temperature can be caused by the suppression of
  the long-range magnetic order.\n\nhttps://events.sinp.msu.ru/event/8/cont
 ributions/333/
LOCATION: НИИЯФ\, ЮК\, Ц-05
URL:https://events.sinp.msu.ru/event/8/contributions/333/
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