[seminar] Seminar na IF-u u četvrtak 18. prosinca u 15:00h - Andrey S. Mishchenko (Japan)

[Osor Barisic]

18. prosinca 2014. (četvrtak) u 15:00 sati 

Institut za fiziku, Bijenička cesta 46, predavaonica u III krilu 





Andrey S. Mishchenko 




RIKEN Center for Emergent Matter Science (CEMS), Japan 




ARPES and optical conductivity of the Hubbard model with electron-boson coupling: equilibrium and pump-probe phenomena 





Angle resolved photoemission spectra (ARPES) [1,2] and optical conductivity (OC) [3,4] of the 2D Hubbard model with strong coupling to bosonic excitations are in good agreement with experiments on underdoped cuprates. Comparison with experiments shows that the effective strength of the electron-boson interaction is suppressed with doping. Analysis of the doping dependence of manifestations of the electron-boson interaction with novel many-polaron diagrammatic Monte Carlo method [5] shows that it is occurs because of suppression of the vertex corrections according to Migdal’s theorem. General analysis shows that the energy scales of electron-electron and electron-boson interactions are very similar and it is difficult to prove or disprove its relevance in the spectroscopic experiments with the systems in equilibrium. Hence, a pump-probe technique is an exclusive route to disentangle different interactions and evaluate its importance. 

Time dynamics of the physical properties and OC of the 2D Hubbard-Holstein model is studied theoretically and experimentally when undoped system is put out of equilibrium by an ultrashort powerful light pulse [6,7]. It is shown that the ultra-fast dynamics of the underdoped cuprates can be explained only in case when strong electron-boson coupling is assumed. 

[1] A. S. Mishchenko and N. Nagaosa, Phys. Rev. Lett. 93, 036402 (2004). 
[2] A. S. Mishchenko et al, EPL 95, 57007 (2011). 
[3] A. S. Mishchenko et al, Phys. Rev. Lett. 100, 166401 (2008). 
[4] G. De Filippis et al, Phys. Rev. B 80, 195104 (2009). 
[5] A. S. Mishchenko, N. Nagaosa and N. Prokof’ev, Phys. Rev. Lett. 113, 166402 (2014). 
[6] G. De Filippis et al, Phys. Rev. Lett. 109, 176402 (2012). 
[7] F. Novelli et al, Nature Comm. 5, 5112 (2014). 



Voditelji seminara IF-a: Nikša Krstulović i Osor Barišić 
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