Magnetic field-dependent dynamics and field-driven metal-to-insulator transition of the half-filled Hubbard model: A DMFT+DMRG study

TL;DR

This study investigates how magnetic fields induce a metal-to-insulator transition in the half-filled Hubbard model using DMFT+DMRG, revealing the splitting of the Kondo resonance and different transition types depending on interaction strength.

Contribution

It introduces a high-resolution spectral density analysis under magnetic fields within DMFT+DMRG, elucidating the transition mechanisms and phase boundaries in the Hubbard model.

Findings

Kondo resonance splits at high magnetic fields

Transition from paramagnetic metal to band insulator

Weak interaction regime shows continuous transition, strong regime shows metamagnetic behavior

Abstract

We study the magnetic field driven metal-to-insulator transition in half-filled Hubbard model on the Bethe lattice, using the dynamical mean-field theory by solving the quantum impurity problem with density-matrix renormalization group algorithm. The method enables us to obtain a high-resolution spectral densities in the presence of a magnetic field. It is found that the Kondo resonance at the Fermi level splits at relatively high magnetic field: the spin-up and spin-down components move away from the Fermi level and finally form a spin polarized band insulator. By calculating the magnetization and spin susceptibility, we clarify that an applied magnetic field drives a transition from a paramagnetic metallic phase to a band insulting phase. In the weak interaction regime, the nature of the transition is continuous and captured by the Stoner's description, while in the strong interaction regime the transition is very likely to be metamagnetic, evidenced by the hysteresis curve. Furthermore, we determine the phase boundary by tracking the kink in the magnetic susceptibility, and the step-like change of the entanglement entropy and the entanglement gap closing. Interestingly, the phase boundary determined from these two different ways are largely consistent with each other.