Spectral properties of a doped frustrated Mott insulator: a slave-fermion study

C. N. SPOSETTI; A. MEZIO; A. E. TRUMPER; L.O. MANUEL

Buenos Aires. Argentina

Workshop; At the Frontiers of Condensed Matter V; 2010

Centro Atomico Constituyentes

We study the spectral properties of the tJ model on the triangular lattice,at zero temperature and at low doping, in order to analyze the electrondynamics in the presence of strong correlation and magnetic  frustration. Werepresent the projected electron operators by means of Schwinger-bosons andslavefermions, and we solve the resulting Hamiltonian in an SU(2)-invariantmean-field approximation. Within  this scheme, there are significantantiferromagnetic correlations up to moderate doping, that strongly affectthe electron dynamics. In general, the spectra exhibit two clearlydistinguishable bands: a heavy  one at the top, with a bandwidth of theorder of the exchange integral J, and a light band below, with atight-binding-like dispersion displaced by the magnetic wave vector Q. Theheavy band has its origin in the dressing of the holes by the spinfluctuations, and it has a relatively small Spectral weight due to thepresence of magnetic frustration, while the light band represents the almostfree motion of the electrons at energies above J. As a consequence of thesespectral features, we observe a transition between an incoherent metal atlow doping and a conventional Fermi liquid for higher doping, driven by thespin fluctuations.