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UID:DSC-21557
DTSTART;TZID=Europe/Berlin:20241218T110000
SEQUENCE:1734503992
TRANSP:OPAQUE
DTEND;TZID=Europe/Berlin:20241218T120000
URL:https://www.dresden-science-calendar.de/calendar/en/detail/21557
LOCATION:IFW\, Helmholtzstraße 2001069 Dresden
SUMMARY:Ueda: Chiral phononics with X-ray techniques 
CLASS:PUBLIC
DESCRIPTION:Speaker: Dr. Hiroki Ueda\nInstitute of Speaker: Center for Phot
 on Science\, Paul Scherrer Inst. (PSI)\, Schweiz\nTopics:\n\n Location:\n 
  Name: IFW (B3E.26\, IFW Dresden)\n  Street: Helmholtzstraße 20\n  City: 
 01069 Dresden\n  Phone: \n  Fax: \nDescription: Chirality is the universal
  concept of defining the handedness of an object\, relevant in different f
 ields\, e.g.\, biology\, chemistry\, and particle physics. In condensed ma
 tter physics\, chiral (quasi-)particles are of recent central interest\, e
 .g.\, chiral fermions\, because of their correlation with emergent phenome
 na and topology. Chiral phonons\, sometimes called circular phonons or pho
 nons with angular momentum\, have attracted the recent rapidly growing int
 erest in the field. Their angular momentum naturally makes the phonon magn
 etic. Indeed\, coherent excitation of chiral phonons was reported to creat
 e a large quasi-DC effective magnetic field [1-3]. Their magnetic characte
 r naturally links magnetism and lattice\, and potentially results in emerg
 ent phenomena and non-trivial approaches to spin-lattice coupling via ligh
 t-matter interaction. Despite the significant interest\, their definition 
 has been ambiguous. The definition of chirality is all the roto-inversion 
 symmetry breaking\, i.e.\, space-inversion symmetry and mirror symmetry. A
  two-dimensional rotational mode\, e.g.\, one at the &amp\;amp\;#915\; poi
 nt [1-3] and one propagating in the rotational plane [4]\, cannot be chira
 l because the rotational plane is a mirror plane from the symmetry point o
 f view. Chiral phonons must be three-dimensional\, which is possible when 
 a rotational mode has a propagation perpendicular to the rotational plane.
    Here\, we demonstrate the presence of chiral phonons in a prototypical 
 chiral crystal\, quartz\, and ferroelectric crystal\, LiNbO3\, by means of
  resonant inelastic X-ray scattering (RIXS) with circularly polarized X-ra
 ys [5\, 6]. Since both chiral phonons and circularly polarized X-ray photo
 ns possess angular momentum\, the RIXS process needs to preserve total ang
 ular momentum\, enabling us to excite chiral phonons based on the selectio
 n rule. We disclosed that circularly polarized X-rays couple to chiral pho
 nons at general momentum points in reciprocal space\, which\, in principle
 \, allows us to measure chiral phonon dispersion. I will also talk about t
 he future perspective of chiral phononics based on X-ray techniques.   [1]
  J. Luo et al.\, Science 382\, 698-702 (2023).  [2] M. Basini et al.\, Nat
 ure 628\, 534-539 (2024).  [3] C. S. Davies et al.\, Nature 628\, 540-544 
 (2024).  [4] H. Zhu et al.\, Science 359\, 579-582 (2018).  [5] H. Ueda et
  al.\, Nature 618\, 946-950 (2023).  [6] H. Ueda et al.\, in preparation.
DTSTAMP:20260719T104923Z
CREATED:20241206T070755Z
LAST-MODIFIED:20241218T063952Z
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