BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:11
UID:UW-Physics-Event-5125
DTSTART:20200409T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260415T041151Z
LAST-MODIFIED:20200326T030949Z
LOCATION:5310 Chamberlin
SUMMARY:*CANCELLED* Electron Hydrodynamics in Graphene: Introduction a
 nd Status\, R. G. Herb Condensed Matter Seminar\, Denis Bandurin\, MIT
DESCRIPTION:Transport in systems with many particles experiencing freq
 uent mutual collisions (such as gases or liquids) has been studied for
  more than two centuries and is accurately described by the theory of 
 hydrodynamics. It has been argued theoretically for a long time that t
 he collective behaviour of charge carriers in solids can also be treat
 ed by the hydrodynamic approach. However\, despite attempts\, until re
 cently very little evidence of hydrodynamic electron transport has bee
 n found.
\n
\nGraphene encapsulated between hexagonal boron nitride (h
 BN) offers an ideal platform to study electron hydrodynamics as it hos
 ts an ultra-clean electronic system with electron-electron collisions 
 being the dominant scattering source above liquid nitrogen temperature
 s. In the first part of my talk we will discuss why electron hydrodyna
 mics has not been observed before and how it manifests itself in graph
 ene. It will be shown that electrons in graphene can behave as a very 
 viscous fluid forming vortices of applied electron current [1\,2]. In 
 the second part\, we will discuss methods which can be applied to meas
 ure electron viscosity and talk about superballistic flow of viscous e
 lectron fluids through graphene point contacts [3]. Then we will talk 
 about the behaviour of electron fluids in the presence of magnetic fie
 ld where I will report the experimental measurements of the odd (Hall)
  viscosity in two dimensions [4]. This dissipationless transport coeff
 icient has been widely discussed in theoretical literature on fluid me
 chanics\, plasma physics and condensed matter physics\, yet\, until no
 w\, any experimental evidence has been lacking\, making the phenomenon
  truly a unicorn. Last but not least\, we will discuss how electron hy
 drodynamics can motivate the development of resonant terahertz detecto
 rs and I will report some recent progress in this direction [5].
\n
\n
 [1] Negative Local Resistance Caused by Viscous Electron Backflow in G
 raphene\, D. A. Bandurin\, A. Principi\, G.H. Auton\, E. Khestanova\, 
 K.S. Novoselov\, I. V Grigorieva\, L.A. Ponomarenko\, A.K. Geim\, and 
 M. Polini\, Science 351\, 1055 (2016).
\n[2] Fluidity Onset in Graphen
 e\, D. A. Bandurin\, A. Shytov\, L. S. Levitov\, R. Krishna Kumar\, A.
  I. Berdyugin\, M. Ben Shalom\, I. V. Grigorieva. A. K. Geim and G. Fa
 lkovich\, Nat. Comm. 9\, 4533 (2018).
\n[3] Superballistic Flow of Vis
 cous Electron Fluid through Graphene Constrictions\, R. Krishna Kumar\
 , D.A. Bandurin\, F.M.D. Pellegrino\, Y. Cao\, A. Principi\, H. Guo\, 
 G.H. Auton\, M. Ben Shalom\, L.A. Ponomarenko\, G. Falkovich\, I. V. G
 rigorieva\, L.S. Levitov\, M. Polini\, and A.K. Geim\, Nat. Phys. 13\,
  1182 (2017).
\n[4] Measuring Hall viscosity of Graphene’s Electron 
 Fluid\, I. Berdyugin\, S. G. Xu\, F. M. D. Pellegrino\, R. Krishna Kum
 ar\, A. Principi\, I. Torre\, M. Ben Shalom\, T. Taniguchi\, K. Watana
 be\, I. V. Grigorieva\, M. Polini\, A. K. Geim and D. A. Bandurin\, Sc
 ience 364\, 6436\, 162-165 (2019). 
\n[5] Resonant Terahertz Detection
  Using Graphene Plasmons\, D. A. Bandurin\, D. Svintsov\, I. Gayduchen
 ko\, S. G. Xu\, A. Principi\, M. Moskotin\, I. Tretyakov\, D. Yagodkin
 \, S. Zhukov\, T. Taniguchi\, K. Watanabe\, I. V. Grigorieva\, M. Poli
 ni\, G. Goltsman\, A. K. Geim and G. Fedorov\, Nat. Comm. 9\, 5392 (20
 18).
\n
\n
URL:https://www.physics.wisc.edu/events/?id=5125
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