[seminar] Podsjetnik na DANAŠNJI seminar na IF-u u 15:00h - Prof. Denis Arčon (Ljubljana)

[Damir Staresinic]

Institut za fiziku, Bijenička cesta 46, 

predavaonica u zgradi Mladen Paić petak, 12. lipnja 2015., u 15:00 sati 
  
Electron correlations, superconductivity and magnetism in orbitally-degenerate molecular solids 
Prof. Denis Arčon 
  
Jožef Stefan Institute and Faculty of mathematics and physics, University of Ljubljana, Slovenia   

  


Light element molecular solids with s/p-based outer electrons in which a fine balance exists between electron-phonon coupling and electron correlation energies can give rise to some most intriguing electronic properties usually associated only with the transition-metal ions. These systems are naturally narrow-band solids where on-site repulsion is comparable to or larger than the electronic bandwidth. Moreover, in cases when the degeneracy of the frontier molecular orbitals is preserved the interplay between the Hund's rule coupling and Jahn-Teller effect lead to a very rich phase diagram where correlated superconducting state borders the Mott-insulating antiferromagnetic phase [1,2]. 

In this talk we will first report on our study of face-centred-cubic (f.c.c.) alkali-doped fullerides, A 3 C 60 (A = alkali metal) with triply-degenerated t 1u frontier molecular orbitals that can be tuned continuously through the bandwidth-controlled antiferromagnetic Mott insulator-metal/superconductor transition by chemical or physical pressure [1,2]. Both competing phases will be evaluated by employing pressure- and temperature-dependent nuclear magnetic resonance (NMR) studies. In particular, the size and the symmetry of the superconducting gap close to the metal/superconductor-insulator boundary will be examined [3,4]. 

Alkali-metal superoxides and sesquioxides (AO 2 and A 4 O 6 ) belong to the similar class of molecular solids showing unusual magnetism that depends on the orbital ordering of π* molecular orbitals [5,6]. The richness of these systems stem from the simultaneous presence of orientational, charge, orbital, and spin degrees of freedom that are strongly coupled as revealed from the comprehensive NMR and EPR studies. 

  

[1] Y. Takabayashi, D. Arčon et al. , Science 323 , 1585 (2009). 
[2] A. Y. Ganin, D. Arčon et al. , Nature 466 , 221 (2010). 
[3] A. Potočnik et al. , Sci. Rep. 4 , 4265 (2014). 
[4] R. H. Zadik et al. , Sci. Adv. 1 , e1500059 (2015). 
[5] D. Arčon et al. , Phys. Rev. B 88 , 224409 (2013). 
[6] T. Knaflič et al. , Phys. Rev. B 91 , 174419 (2015). M. Klanjšek et al., arXiv:1409.4818. 

  

E-mail: denis.arcon at ijs.si 

  
  
  
Voditelji seminara IF-a: Nataša Vujičić i Damir Starešinić 
  


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