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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-9583
DTSTART:20260305T160000Z
DTEND:20260305T170000Z
DTSTAMP:20260413T084157Z
LAST-MODIFIED:20260211T202025Z
LOCATION:5310 Chamberlin Hall
SUMMARY:Dynamical breaking of inversion symmetry\, strong second harmo
 nic generation\, and ferroelectricity with nonlinear phonons\, R. G. H
 erb Condensed Matter Seminar\, Egor Kiselev \, MPIPKS
DESCRIPTION:I will show how crystalline inversion symmetry can be dyna
 mically broken by optical phonons with generic\, hardening Kerr-like n
 on-linearities. The symmetry-broken state is reached through a dynamic
 al phase transition that can be accessed by driving close to half the 
 phonon resonance. After going through an instability\, the system sett
 les to a steady state with inversion-symmetry breaking phonon trajecto
 ries and strong second harmonic generation. The time averaged position
 s of the atoms are displaced relative to equilibrium\, resulting in a 
 rectification of the driving signal. This leads to a dynamical dipolar
 \, ferroelectric response that shows features like hysteresis and memo
 ry effects\, known from equilibrium ferroelectrics.  
URL:https://www.physics.wisc.edu/events/?id=9583
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