ELFT HÍRADÓ

[Andras Palyi <andraspalyi AT caesar.elte.hu>]

Kedves Kollégák!

2016. szeptember 27-én kedden 14:15-től Gyenis András (Princeton University, 
USA) tart előadást a BME Fizikai Intézetében. Előadásának címe:

"Imaging electronic states on topological Dirac and Weyl semimetals using 
scanning tunneling microscopy”

Az előadás helyszíne a BME Elméleti Fizika Tanszék szemináriumi szobája. (BME 
F épület 3. lépcsőház, magasföldszint)

Kivonat: 
“Following the intense studies on topological insulators, significant efforts 
have recently been devoted to the search for gapless topological systems. 
These materials not only broaden the topological classification of matter but 
also provide a condensed matter realization of various relativistic particles 
and phenomena previously discussed mainly in high energy physics. Weyl 
semimetals host massless, chiral, low-energy excitations in the bulk 
electronic band structure, whereas a symmetry protected pair of Weyl fermions 
gives rise to massless Dirac fermions. On the surface, topological semimetals 
harbor protected states, with arced Fermi surface contours that are predicted 
to propagate through the bulk when their momentum matches that of the surface 
projections of the bulk's nodes. We employed scanning tunneling 
microscopy/spectroscopy to explore the behavior of electronic states both on 
the surface and in the bulk of topological semimetal phases. By mapping the 
quasiparticle interference and emerging Landau levels at high magnetic field 
in Dirac semimetals Cd3As2 and Na3Bi, we observed extended Dirac-like bulk 
electronic bands. Quasiparticle interference imaged on Weyl semimetal TaAs 
demonstrated the predicted momentum dependent delocalization of Fermi arc 
surface states in the vicinity of the surface-projected Weyl nodes. Our 
findings provide evidence that Weyl nodes act as sinks for electron transport 
on the surface of these materials.

S. Jeon, B. Zhou et al. Nature Materials 13, 851 (2014)
S. Kushwaha et al. APL Materials 3, 041504 (2015) 
H. Inoue, A. Gyenis et al. Science 351, 1184 (2016)”

Minden érdeklődőt szeretettel várunk.

A szemináriumsorozat további programja: 
http://exotic.phy.bme.hu/seminars.html

Üdvözlettel,
Pályi András