# Ferromagnetic Instability for single-band Hubbard model in the strong-coupling regime

## TL;DR

This study investigates ferromagnetic instability in a doped single-band Hubbard model using dynamical mean-field theory and quantum Monte Carlo simulations, highlighting the role of high-energy density of states in ferromagnetism.

## Contribution

It demonstrates the importance of high-energy DOS in stabilizing ferromagnetism in the strong-coupling regime, contrasting with weak-coupling theories.

## Key findings

- Ferromagnetic order appears in the hypercubic lattice but not in the Bethe lattice.
- Slower decay of high-energy DOS enhances ferromagnetic stability.
- High-energy DOS significantly influences ferromagnetic emergence in strong coupling.

## Abstract

We study a ferromagnetic instability in a doped single-band Hubbard model by means of dynamical mean-field theory with the continuous-time quantum Monte Carlo simulations. Examining the effect of the strong correlations in the system on the hypercubic and Bethe lattice, we find that the ferromagnetically ordered state appears in the former, while it does not in the latter. We also reveal that the ferromagnetic order is more stable in the case that the noninteracting DOS exhibits a slower decay in the high-energy region. The present results suggest that, in the strong-coupling regime, the high-energy part of DOS plays an essential role for the emergence of the ferromagnetically ordered state, in contrast to the Stoner criterion justified in the weak interaction limit.