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SUMMARY:Visualizing the response of topological materials under Coulomb an
 d magnetic perturbations
DTSTART:20160530T110000
DTSTAMP:20260510T081849Z
UID:d0f52196292929175c2c63dcc08e0c86105fd8b900b811f5ccce2dae
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Paolo Sessi\nExperimentelle Physik II\, Physikalisches Ins
 titut\, Universität Würzburg\nThe recent discovery of materials hosting 
 topologically protected electronic states opened a new era in condensed ma
 tter. Since topological properties usually manifest at boundaries\, scanni
 ng probe techniques are ideal tools to visualize them with both high spati
 al and energy resolution. In my talk\, I will report recent experiments th
 at not only allow to visualize the presence of these unconventional bounda
 ry modes\, but also to demonstrate some of their unusual properties. In pa
 rticular\, I will discuss recent efforts focused on the controlled manipul
 ation of topological states once coupled to well-defined perturbations. I 
 will first examine topological insulators and show that\, contrary to what
  generally believed\, magnetic order and gapless states can coexist. I wil
 l illustrate how this is intimately related to the dual nature of magnetic
  dopants\, which leads to the emergence of a two-fluid behavior where the 
 competition in between opposite trends\, i.e. gap opening vs. gap-closing\
 , is ultimately linked to the localized vs. delocalized nature of the pert
 urbations-induced quasiparticles. I will then report more recent experimen
 ts on the new class of materials known as Weyl semimetals. The surfaces of
  these compounds host a new class of topologically protected electronic st
 ates that form Fermi arcs\, which correspond to unclosed contours connecti
 ng Weyl points of opposite chirality. By quasi particle interference mappi
 ng\, we detect the emergence of a rich scattering scenario. I will discuss
  how our experiments allow for a detailed verification of existing theoret
 ical proposals dealing with intra- and inter-arc scattering events. More g
 enerally\, I will discuss how electronic states propagate in these materia
 ls where the lack of inversion symmetry\, combined with strong spin-orbit 
 coupling\, gives rise to a plethora of multi-band spin-split states.
LOCATION:aquarium (PH L1 503)
STATUS:CONFIRMED
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