Speaker:

Alberto Nocera, University of Tennessee
Event Date and Time:

Thu, 2018-01-25 14:00 - 15:00
Location:

Hennings #318
Local Contact:

Marcel Franz Dynamical response functions of strongly correlated quantum systems provide crucial infor-

mation about their complex physical behavior. For example, in layered high Tc superconduc-

tors, pairing could be linked to the unusual structure of spin excitations with a spin gap at low

energies and a magnetic resonance with an universal hourglass dispersion. Angle resolved pho-

toemission spectroscopy represents another invaluable tool, providing direct access to the pairing

symmetry, quasi-particle dispersions, and band structure topology. However, the computation of

response functions starting from model Hamiltonians for correlated systems in layered geometries

is a formidable task because of the absence of accurate many-body tools, particularly when many

orbitals are active. Fortunately, in certain cases layered materials are made of weakly coupled

quasi-one dimensional building blocks, such as chains or ladders. This oers to theorists the

unique opportunity to study both the ground-state and excitation spectra of these quasi-one di-

mensional systems with numerically exact techniques, such as the density matrix renormalization

group method (DMRG). In the rst part of the presentation, I will show DMRG results for the

dynamical spin structure factor of the Hubbard model in a two-leg ladder geometry [1], provid-

ing a criterion to link the pairing strength directly to the magnetic excitation spectrum. In the

second part, I will show how the lattice aects the properties of the photoemission spectrum of

a hole doped one-dimensional Hubbard chain [2]. Because of its importance for real applications,

I will also address the eects of a nite temperature on the photoemission spectrum in the Mott

insulating regime, showing a redistribution of spectral weight inside the Mott gap [3]. Finally, I

will discuss the implications of our results for experiments and outline future directions of research.

References

[1] A. Nocera, N. D. Patel, E. Dagotto, G. Alvarez, Phys. Rev. B 96, 205120 (2017).

[2] A. Nocera, M. Soltanieh-ha, C. A. Perroni, V. Cataudella, A. E. Feiguin, Phys. Rev. B 90,

195134 (2014).

[3] A. Nocera, F. H. L. Essler, A. E. Feiguin, arXiv:1710.06452 [cond-mat.str-el].