Université de Fribourg

Alleviating the sign problem in quantum Monte Carlo simulations of spin-orbit-coupled multiorbital Hubbard models

Kim, Aaram J. ; Werner, Philipp ; Valentí, Roser

In: Physical Review B, 2020, vol. 101, no. 4, p. 045108

We present a strategy to alleviate the sign problem in continuous-time quantum Monte Carlo (CTQMC) simulations of the dynamical-mean-field-theory (DMFT) equations for the spin-orbit-coupled multiorbital Hubbard model. We first identify the combinations of rotationally invariant Hund coupling terms present in the relativistic basis which lead to a severe sign problem. Exploiting the fact that...

Université de Fribourg

Spin-freezing and the Sachdev-Ye model

Werner, Philipp ; Kim, Aaram J. ; Hoshino, Shintaro

In: EPL (Europhysics Letters), 2018, vol. 124, no. 5, p. 57002

Spin-freezing is the origin of bad-metal physics and non-Fermi liquid (non-FL) properties in a broad range of correlated compounds. In a multi-orbital lattice system with Hund coupling, doping of the half-filled Mott insulator results in a highly incoherent metal with frozen magnetic moments. These moments fluctuate and collapse in a crossover region that is characterized by unusual non-Fermi...

Université de Fribourg

$\mathbf{J}$ freezing and Hund’s rules in spin-orbit-coupled multiorbital Hubbard models

Kim, Aaram J. ; Jeschke, Harald O. ; Werner, Philipp ; Valentí, Roser

In: Physical Review Letters, 2017, vol. 118, no. 8, p. 086401

We investigate the phase diagram of the spin-orbit-coupled three orbital Hubbard model at arbitrary filling by means of dynamical mean-field theory combined with the continuous-time quantum Monte Carlo method. We find that the spin-freezing crossover occurring in the metallic phase of the nonrelativistic multiorbital Hubbard model can be generalized to a J-freezing crossover, with J=L+S, in...