Calendario Attività

Quantum simulations of dynamical response functions for strongly correlated quasi-one dimensional materials

Categoria
Seminario
Data
16 Maggio 2018 10:00 - 11:00
Luogo
14 - 15 IV piano St. 9
Affiliation
Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee USA
Area di Ricerca
Superconduttivita', Sistemi fortemente correlati, Eterostrutture e loro applicazioni

In condensed matter physics, inelastic neutron scattering (INS) and resonant inelastic x-ray scattering (RIXS) spectroscopies represent ideal probes for studying the dynamical response of strongly correlated quantum materials. While INS is generally the method of choice for the investigation of magnetic excitations, over the past decade RIXS has been established as a powerful complementary technique to study the energy-momentum structure of charge, orbital, lattice, and magnetic excitations of these systems. In two dimensional materials, the computation of dynamical response functions starting from model Hamiltonians is often 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 offers the unique opportunity to study both the ground-state and excitation spectra of these systems with numerically exact techniques, such as the density matrix renormalization group method (DMRG). In the first 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], providing a criterion to link the pairing strength directly to the magnetic excitation spectrum. In the second part, I will present a method for computing RIXS spectra in one-dimensional systems using DMRG [2]. With this new procedure, I computed the low-energy magnetic excitations observed in Cu L-edge RIXS for the challenging corner shared CuO4 chains. Finally, I will discuss the implications of the 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, U. Kumar, N. Kaushal, G. Alvarez, E. Dagotto, S. Johnston, arXiv:1803.11248 [cond-mat.str-el] (2018).

 
 

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