%0 Book Section %1 statphys23_0620 %A Tarzia, M. %A Biroli, G. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K correlated disordered electrons glass glasses quantum spin statphys23 strongly systems topic-9 transition %T Quantum glassiness in the Hubbard-Heisenberg model on the random graph in the large-n limit %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=620 %X The theoretical study of the interplay between quantum fluctuations and self-generated glassy behavior is still in its infancy although there have been recent progress on the subject. From the experimental point of view there are many examples of systems almost pure (without quenched disordered) that display slow dynamics and glassy behaviors. One example are geometrically frustrated quantum magnets on polychlore lattices, that exhibit a clear spin-glass transition, although they are considered to be essentially free of quenched disorder. In order to understand these phenomena, we have studied the fermionic Hubbard-Heisenberg model in the large-$n$ limit, and derived its phase diagram. At high temperature a uniform phase is found, which becomes unstable as the temperature is lowered, and a continuous spin-glass like transition to a disordered phase occurs. In the glassy phase a non-trivial distribution of the overlaps between different states is observed, and a pseudo-gap in the electron spectrum around the Fermi level is shown to emerge, in agreement with what found in a mean-field theory for the three-dimensional Coulomb Glass. The presence of the pseudogap can be related to the occurrence of a finite temperature glass transition, accompanied by a replica symmetry breaking, and by the ensuing ergodicity breaking. Finally, at low hopping parameter $t$, also a dimerized phase is observed. These results might give useful insights to understand recent experimental observations, and shed new light on new quantum phases of matter.

@incollection{statphys23_0620, abstract = {The theoretical study of the interplay between quantum fluctuations and self-generated glassy behavior is still in its infancy although there have been recent progress on the subject. From the experimental point of view there are many examples of systems almost pure (without quenched disordered) that display slow dynamics and glassy behaviors. One example are geometrically frustrated quantum magnets on polychlore lattices, that exhibit a clear spin-glass transition, although they are considered to be essentially free of quenched disorder. In order to understand these phenomena, we have studied the fermionic Hubbard-Heisenberg model in the large-$n$ limit, and derived its phase diagram. At high temperature a uniform phase is found, which becomes unstable as the temperature is lowered, and a continuous spin-glass like transition to a disordered phase occurs. In the glassy phase a non-trivial distribution of the overlaps between different states is observed, and a pseudo-gap in the electron spectrum around the Fermi level is shown to emerge, in agreement with what found in a mean-field theory for the three-dimensional Coulomb Glass. The presence of the pseudogap can be related to the occurrence of a finite temperature glass transition, accompanied by a replica symmetry breaking, and by the ensuing ergodicity breaking. Finally, at low hopping parameter $t$, also a dimerized phase is observed. These results might give useful insights to understand recent experimental observations, and shed new light on new quantum phases of matter.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Tarzia, M. and Biroli, G.}, biburl = {https://www.bibsonomy.org/bibtex/2f834b6b0f7874c02f9facc6341578078/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {07122624fe29bb8dabadf4a0df770e1c}, intrahash = {f834b6b0f7874c02f9facc6341578078}, keywords = {correlated disordered electrons glass glasses quantum spin statphys23 strongly systems topic-9 transition}, month = {9-13 July}, timestamp = {2007-06-20T10:16:25.000+0200}, title = {Quantum glassiness in the Hubbard-Heisenberg model on the random graph in the large-n limit}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=620}, year = 2007 }