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セミナーのお知らせ: Mikhail Portnoi氏 (Professor, University of Exeter)
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日時：２０２６年８月２５日（火）13:00～14:30
場所：東京大学理学部4号館1723号室
講演者：Mikhail Portnoi氏
(Professor, University of Exeter)
講演題目:Trapping electrons in two-dimensional Dirac semimetals
Abstract
【Abstract】
In Westminster Abbey, in the nave near Newton’s monument, lies a memorial stone to Paul Dirac. The inscription on the stone includes the relativistic wave equation for the electron: the Dirac equation. At the turn of the 21st century, it was discovered that this eponymous equation was not solely the preserve of particle physics. The isolation of graphene by Andre Geim and Konstantin Novoselov in Manchester led to the exploration of a novel class of materials --Dirac materials-- whose electrons behave as Dirac particles. While the high mobility of these quasi-relativistic electrons is attractive from the perspective of potential ultrafast devices, it also presents a distinct challenge: how can Dirac particles be confined so as to avoid inherently leaky devices.
In my talk, I will discuss the unconventional quantum tunnelling of Dirac particles, explain strategies for creating electrostatically bound states, and briefly review some pioneering experiments aimed at trapping Dirac electrons. I will show how bound states may arise in gapless Dirac materials despite the phenomenon of Klein tunnelling. I will also consider the coupling of two ultra-relativistic particles and discuss how the presence of dark-matter-like, silent, immobile bielectron zero-energy vortices may explain a range of poorly understood experiments in gated graphene structures at low doping.
Selected references:
R.R. Hartmann, N.J. Robinson, M.E. Portnoi, Phys. Rev. B 81, 245431 (2010).
C.A. Downing, D.A. Stone, and M.E. Portnoi, Phys. Rev. B 84, 155437 (2011).
D.A. Stone, C.A. Downing, and M.E. Portnoi, Phys. Rev. B 86, 075464, (2012).
R.R. Hartmann and M.E. Portnoi, Phys. Rev. A 89, 012101 (2014).
C.A. Downing et al., Phys. Rev. B 92, 165401 (2015).
C.A. Downing and M.E. Portnoi, Phys. Rev. B 94, 165407 (2016).
C.A. Downing and M.E. Portnoi, Journal of Physics: Condensed Matter 29, 315301 (2017).
C.A. Downing and M.E. Portnoi, Nature Communications 8, 897 (2017).
C.A. Downing and M.E. Portnoi, Phys. Status Solidi B 256, 1800584 (2019) (Feature Article).
C.A. Downing, M.E. Portnoi “Quantum confinement in Dirac-like nanostructures” in Encyclopedia of Condensed Matter Physics, edited by T. Chakraborty (Elsevier, Amsterdam, 2024).
使用言語：English/英語
紹介教員：小西 邦昭
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