CMSP Section announces seminar on Thursday

[Cond.Matt. & Stat.Mech.Section]

SEMINAR on    Disorder and strong electron correlations

 


Thursday, 14 March -  11:30 a.m.

 

Luigi Stasi Seminar Room,  Leonardo Building - first floor

 

Andrea PERALI    (University of Camerino)


"Pseudogap in ultracold Fermi gases:    Theory, experiments, and QMC simulations"


Abstract


The origin of the pseudogap is widely debated for  cuprate superconductors. The main controversy concerns whether superconductivity and the pseudogap phase are competing with each other or are manifestations of the same phenomenon. In the latter case, pairing fluctuations would extend above the critical temperature (Tc) the effects of the pairing gap below Tc [1].

A contribution to settle this controversy can be obtained by ultracold fermions, which are free of the structural complications of cuprates and where only pairing fluctuations are present above Tc. In these systems, the inter-particle attraction can be varied by Fano-Feshbach resonances as to amplify the effects of pairing fluctuations.

In this context, wave-vector resolved radio frequency spectroscopy data for an ultracold trapped Fermi gas are reported for several couplings at Tc, and analyzed  by a pairing-fluctuation theory. We show that the non-Fermi-liquid behavior associated with the presence of a pseudogap coexists with a robust remnant Fermi surface over a wide coupling range, which sets the boundary of the  pseudogap phase [2,3,4].

Moreover, the properties of the pseudogap phase obtained within the t-matrix approach are compared with the outcomes of recent quantum Monte Carlo (QMC) ab initio simulations [5,6].

Once the pseudogap has been characterized in ultracold fermions, we compare the temperature dependence of the spectral intensity suppression obtained within our theory with the one measured in cuprates by angular resolved photoemission spectroscopy (ARPES) [7].

 
References


[1] A. Perali, P. Pieri, G.C. Strinati, and C. Castellani, Phys. Rev. B 66, 024510 (2002).

[2] J.P. Gaebler, J.T. Stewart, T.E. Drake, D.S. Jin,  A. Perali, P. Pieri, and G. C. Strinati, Nature Physics 6, 569 (2010).

[3] A. Perali, F. Palestini, P. Pieri, G.C. Strinati,  J. T. Stewart, J. P. Gaebler, T. E. Drake, and D. S. Jin,  Phys. Rev. Lett. 106, 060402 (2011).

[4] F. Palestini, A. Perali, P. Pieri, and G.C. Strinati,  Phys. Rev. B 85, 024517 (2012).

[5] P. Magierski, G. Wlazlowski and A. Bulgac, Phys. Rev. Lett. 107, 145304 (2011).

[6] G. Wlazlowski, P. Magierski, J. E. Drut, A. Bulgac, and K. J. Roche, Phys. Rev. Lett. 110, 090401 (2013).

[7] T. Kondo, Y. Hamaya, A. D. Palczewski, T. Takeuchi, J. S. Wen, Z. J. Xu, G. Gu, J. Schmalian & A. Kaminski, Nature Physics 7, 21 (2011).