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SUMMARY:Optical Control of Chirality and Ferroaxial Domains
DTSTART:20260122T090000Z
DTEND:20260122T100000Z
DTSTAMP:20260503T013300Z
UID:indico-event-49963@agenda.infn.it
DESCRIPTION:Speakers: Michael Fechner (Max Planck Institute for the Struct
 ure and Dynamics of Matter\, Hamburg (Germany))\n\nFerroic orders arise fr
 om collective quantum interactions that stabilize long-range electronic ar
 rangements. Here\, we demonstrate optical control of such orders using int
 ense terahertz (THz) pulses. Two key cases are presented.\nFirst\, we show
  that linearly polarized THz pulses can induce chirality [1] in the achira
 l piezoelectric boron phosphate (BPO₄). Because chirality requires the s
 imultaneous breaking of all mirror and roto-inversion symmetries\, its ind
 uction in nonchiral systems is highly nontrivial. We find that resonant ex
 citation of one of two orthogonal\, degenerate vibrational modes generates
  a chiral order parameter\, with handedness determined by the selected mod
 e.\nSecond\, we demonstrate switching of ferroaxial domains [2]. Unlike co
 nventional ferroics\, ferroaxial states are bistable yet preserve both inv
 ersion and time-reversal symmetry\, making them robust against depolarizin
 g fields but difficult to manipulate. By coherently driving circularly pol
 arized THz phonon modes\, we create an effective axial field that enables 
 ultrafast domain switching. The switched domains remain stable for hours a
 nd can be reversed with pulses of opposite helicity.\nOur results establis
 h a pathway for optical control of chirality and ferroaxial order\, openin
 g opportunities for ultrafast\, robust information storage.\n[1] Z. Zeng\,
  et al.\, Science 387\, 431 (2025)\n[2] Z. Zeng\, et al. arXiv:2506.10682\
 , (2025)\n\nhttps://agenda.infn.it/event/49963/
LOCATION:Aula Rasetti (Dip. di Fisica - edificio G. Marconi)
URL:https://agenda.infn.it/event/49963/
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