[seminar] Seminar na IF-u, 20. prosinca 2013. u 10:00h

[Niksa Krstulovic]

Institut za fiziku, Bijenička cesta 46, 

Velika predavaonica (I krilo IF-a) petak, 20. prosinca 2013., u 10:00 sati 
Correlation Effects and Itinerant Particles 

dr.sc. Neven Barišić 


Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 

1040 Vienna, Austria 





Understanding the nature of quasiparticles in the presence of strong correlations has been one of the 

most challenging topics in physics. In this contribution, I will revisit several very different systems and 

demonstrate that a key step in descriptions of their physical properties is related to the itinerant 

quasiparticles and their interaction with localized degrees of freedom. Outstanding examples of such 

systems are the high-temperature superconductors. Contrary to conventional wisdom, we find that 

the in-plane resistivity in the pseudogap phase (1) of the model cuprate HgBa2CuO4+δ (2,3) exhibits 

a quadratic temperature dependence of the resistivity (ρ ~ T 2 ), the same behavior that is seen in 

conventional Fermi liquids (4). This insight motivated collaborative optical conductivity measurements 

that indeed yield the quadratic frequency dependence and temperature-frequency scaling expected 

for a correlated Fermi liquid (5). We arrive at the unexpected conclusion that, even close to the 

Mott-insulating state at zero doping, the cuprates behave like Fermi liquids. 

By combining our dc resistivity results with published data for three structurally more complex cuprates, 

we are able to obtain the universal sheet resistance throughout most of the temperature-doping phase 

diagram (4). Current theoretical models can now be benchmarked against this universal result. Together 

with microwave results for HgBa 2 CuO 4+δ and several other compounds (6, 7), we arrive at a revised phase 

diagram for the cuprates. Finally, I will demonstrate that a combined analysis of the dc and optical conductivities in the 

optimally-doped 122-iron pnictide also reveals a T 2 dependence of the normal state transport scattering rate 

(8, 9). Although the iron-pnictides are in many respects different from the cuprates, this 

observation indicates that, quite generally, the superconductivity in “unconventional” superconductors 

evolves from a conventional Fermi-liquid-like state. 



1. Y. Li, V. Baledént, N. Barišić, Y. Cho, B. Fauque, Y. Sidis, G. Yu, X. Zhao, P. Bourges, M. Greven. Nature 

455, 372 (2008). 

2. N. Barišić, Y. Li, X. Zhao, Y. Cho, G. Chabot-Couture, G. Yu, M. Greven. Phys. Rev. B 78, 054518 (2008). 

3. N. Barišić, S. Badoux, M. K. Chan, C. Dorow, W. Tabis, B. Vignolle, G. Yu, J. Béard, X. Zhao, C. Proust, 

and Martin Greven. Nature Physics 9, 761 (2013). 

4. N. Barišić, Y. Li, G. Yu, X. Zhao, M. Dressel, A. Smontara, M. Greven. Proc. Natl. Acad. Sci. 110, 12235 

(2013). 

5. S. I. Mirzaei, D. Stricker, J. N. Hancock, C. Berthod, A. Georges, E. van Heumen, M. K. Chan, X. Zhao, Y.Li, M. Greven, N. Barišić, D. van der Marel. Proc. Natl. Acad. Sci. 110, 5774 (2013). 

6. M. S. Grbić, N. Barišić, A. Dulčić, I. Kupčić, Y. Li, X. Zhao, G. Yu, M. Dressel, M. Greven, and M. Požek, 

Phys. Rev. B 80, 094511 (2009). 

7. M. S. Grbić, M. Požek, D. Paar, V. Hinkov, M. Raichle, D. Haug, B. Keimer, N. Barišić, and A. Dulčić, 

Phys. Rev. B 83, 144508 (2011). 

8. N. Barišić, D. Wu, M. Dressel, L. J. Li, G. H. Cao, and Z. A. Xu. Phys. Rev. B 82, 054518 (2010). 

9. D. Wu, N. Barišić, P. Kallina, A. Faridian, B. Gorshunov, N. Drichko, L. J. Li, X. Lin, G. H. Cao, Z. A. Xu, N. 

L. Wang, and M. Dressel. Phys. Rev. B 81, R100512 (2010). 







Voditelji seminara IF-a: Nikša Krstulović i Osor Bari šić 


************************* 
Nikša Krstulović, PhD 
Research associate 

Institute of Physics 
Bijenicka 46 
HR-10000 Zagreb, Croatia 

Phone: 00385 1 4698 872 
00385 1 4698 851 
Fax: 00385 1 4698 889 

http://www.ifs.hr/ 
http://spectra.ifs.hr/ 
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