[seminar] IF

[Ticijana Ban]

Poštovani,

Obavještavam Vas o održavanju seminara na Institutu za fiziku, Bijenička cesta 46, predavaonica u zgradi Mladena Paića DANAS u ponedjeljak,  3. rujna 2007. u 15:00 sati.

Seminar pod naslovom Magnetism and Electronic Correlation in Quasi-One-Dimensional System održat će prof. Maurício D. Coutinho-Filhosa sa Sveučilišta u Pernambucu, Brazil.
Kratki sažetek predavanja možete pronaći u nastavku poruke.

Srdačan pozdrav i isprike na kasnoj obavijesti,

Ticijana Ban
_______________________________________________________________________________________________________________________

 Magnetism and Electronic Correlation in Quasi-One-Dimensional System

 

Maurício D. Coutinho-Filho

Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50680-901, Recife-PE, Brazil

 

  Low-dimensional correlated electron systems have attracted great attention in the last two decades. The reason dates back to Anderson's proposal in 1987 that the t-J version of the Hubbard model might carry the main mechanisms underlying high-Tc superconductivity. Despite that this remains an open issue, the above suggestion have fertilized intensive investigations on many related fundamental topics, such us itinerant electron magnetism, Mott metal-insulator transitions and quantum critical phenomena. Amongst several phases of interest, we mention the possibility of realization of spiral, Nagaoka and resonating-valence-bond (RVB) states, spatially separated phases and Luttinger liquid behavior, which may present strong deviations from the Landau Fermi liquid theory.

  In this talk we discuss several results related to quasi-one-dimensional systems, in particular those referring to Hubbard, t-J and Heisenberg ABC and AB2 chains, which display unit cell topologies that allow the occurrence of long-range ferrimagnetism at half-filled band. We show that the magnetic excitations strongly depend on the Coulomb coupling, and that the antiferromagnetic massive excitation gives rise to a plateau in the field-dependent magnetization curve. The presence of doping (holes away from half filling) causes the appearance of all the above-mentioned phases for adequate values of the Coulomb repulsion, while the existence of frustrated Heisenberg interactions induces strong quantum fluctuations, which also causes the suppression of the ferrimagnetic ordering. Moreover, we highlight the connections with the physics of two-dimensional and ladder systems.    

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.phy.hr/pipermail/seminar/attachments/20070903/645cc74d/attachment.html