Magnetic quantum criticality: dynamical mean-field perspective

TL;DR

This paper explores magnetic quantum phase transitions in correlated metals using dynamical mean-field theory, highlighting the role of Fermi surface features and potential effects of spatial correlations.

Contribution

It provides a detailed dynamical mean-field analysis of magnetic quantum criticality in the Hubbard model, emphasizing the influence of Kohn-anomalies and Fermi surface geometry.

Findings

Kohn-anomalies influence quantum critical behavior

Phase diagram shaped by Fermi surface features

Potential modifications from spatial correlations beyond DMFT

Abstract

We investigate the magnetic quantum phase-transitions in bulk correlated metals at the level of dynamical mean-field theory. To this end, we focus on the Hubbard model on a simple cubic lattice as a function of temperature and electronic density, determining the different regimes of its magnetic transition - classical, quantum critical, and quantum disordered - as well as the corresponding critical exponents. Our numerical results, together with supporting mean-field derivations, demonstrate how the presence of Kohn-anomalies on the underlying Fermi surface does not only drive the quantum critical behavior above the quantum critical point, but shapes the whole phase diagram around it. Finally, after outlining the impact of different Fermi surface geometries on quantum criticality, we discuss to what extent spatial correlations beyond dynamical mean-field might modify our findings.