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SUMMARY:Topological Insulators - a New State of Matter
DTSTART:20160509T161500
DTEND:20160509T171500
DTSTAMP:20260504T081851Z
UID:acda141165cdbc78f168a094ed014ecd48a184ef02b73dac42da5028
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Laurens W. Molenkamp\nTopological insulators are a novel
  class of materials that exhibit a novel state of matter – while the ins
 ide (bulk) of the materials are electrical insulating\, their surface is m
 etallic. This effect occurs because the band structure of the materials is
  topologically different (in a mathematical sense) from the outside world.
 \nThis talk describes our discovery of this type of behavior while studyin
 g the charge transport properties of thin\, two-dimensional layers of the 
 narrow-gap semiconductor HgTe. These layers exhibit the quantum spin Hall 
 effect\, a quantized conductance which occurs when the bulk of the materia
 l is insulating. Using various tricks one can show that the transport occu
 rs along one-dimensional\, spin-polarized channels at the edges of the sam
 ple.\nAlso thicker HgTe samples can be turned into topological insulators\
 , but now the surface states are two-dimensional metallic sheets. The meta
 l in these sheets is rather exotic in that the band structure is similar t
 o that encountered for elementary particles – the charge is carried by s
 o-called Dirac fermions. This means that experiments on these layers can b
 e used to test certain predictions from particle theory that are difficult
  to access otherwise.\nAs an example\, I will describe experiments where a
  supercurrent is induced in the surface states by contacting these structu
 res with Nb electrodes. AC investigations indicate that the induced superc
 onductivity is strongly influenced by the Dirac nature of the surface stat
 es.We present strong evidence for the presence of a gapless Andreev mode i
 n our junctions.
LOCATION:EPFL\, CE3 http://plan.epfl.ch/?zoom=20&recenter_y=5864182.9707&r
 ecenter_x=731341.22227&layerNodes=fonds\,batiments\,labels\,information\,p
 arkings_publics\,arrets_metro\,transports_publics&floor=1&q=ce3
STATUS:CONFIRMED
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