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SUMMARY:Observation of Pines' Demon in Sr2RuO4 with Momentum-Resolved EELS
  - Peter Abbamonte (UIUC)
DTSTART:20240605T150000Z
DTEND:20240605T160000Z
UID:TALK217531@talks.cam.ac.uk
CONTACT:Lucas Sá
DESCRIPTION:The characteristic excitation of a metal is its plasmon\, whic
 h is a quantized sound wave in its valence electron density. In 1965\, Dav
 id Pines predicted that a distinct type of plasmon\, which he named a "dem
 on\," could exist in multiband metals that contain more than one species o
 f charge carrier. Consisting of electrons in two different bands beating o
 ut-of-phase\, demons are acoustic excitations\, meaning they are “massle
 ss\,” meaning their energy tends toward zero as the momentum q -> 0. Dem
 ons may therefore play a central role in the low-energy physics of multiba
 nd metals. However\, demons are neutral excitations that do not couple to 
 light\, so they have never been observed experimentally\, at least in an e
 quilibrium\, 3D material.\n\nIn this talk I will present the observation o
 f a demon in the multiband metal Sr2RuO4. Formed of electrons in the β an
 d γ bands\, the demon is gapless with critical momentum qc = 0.08 recipro
 cal lattice units and room temperature velocity v = 1.065(120)×105 m/s. T
 his study confirms a 67-year old prediction and suggests that demons may b
 e a widespread feature of multiband metals.\n\n*A. A. Husain\, et al.\, Na
 ture 621\, 66 (2023)
LOCATION:Small Lecture Theatre\, Cavendish Laboratory\, J.J. Thomson Avenu
 e
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