Prof. Denis Arčon: Electron correlations in light-element molecular solids

Date of publication: 23. 10. 2014
Monday physics colloquium
Ponedeljek, 27. oktober 2014, ob 16:15 v predavalnici F1, FMF UL, Jadranska 19, Ljubljana

Pred predavanjem vse udeležence vabimo na čaj!  

Povzetek:

   Electron correlations in light-element molecular solids  

   Public lecture before the promotion to full professor (Javno predavanje pred izvolitvijo v naziv redni profesor) 

   Prof. Denis Arčon, Faculty of mathematics and physics, University of Ljubljana  & Jožef Stefan Institute Ljubljana 

  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 report on recent comprehensive studies of (i) bandwidth-controlled antiferromagnetic Mott insulator-metal/superconductor transition in face-centred-cubic (f.c.c.) alkali-doped fullerides, A3C60 (A = alkali metal) [1-3], (ii) the orbital ordering of π molecular orbitals in magnetic alkali-metal sesquioxide (A4O6) and superoxide (AO2) molecular solids [4] and (iii) isostructural superconducting rare-earth sesquicarbide (Ln2C3, Ln = La, Y) [5]. The richness of these families stem from the simultaneous presence of orientational, charge, orbital, and spin degrees of freedom that are strongly coupled as also revealed from our comprehensive magnetic resonance 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] D. Arčon et al., Phys. Rev. B 88, 224409 (2013).

   [5] A. Potočnik, et al., Phys. Rev. B 90, 104507 (2014).

 

E-mail: denis.arcon@ijs.si