Identification of non-Fermi liquid fermionic self-energy from quantum Monte Carlo data

Quantum Monte Carlo (QMC) simulations offer unbiased insights into correlated electron systems at quantum critical points (QCPs), enabling verification or refutation of non-Fermi liquid (NFL) behavior theories. This paper introduces a framework to separate thermal and quantum effects in finite-temperature QMC data, thereby extracting zero-temperature NFL physics. Applying this method to 2D fermions near an Ising ferromagnetic QCP, the zero-temperature fermionic self-energy Σ(ω) is extracted, showing good agreement with the Eliashberg theory's ω²/³ scaling at low frequencies. This opens new avenues for QMC studies of quantum critical metals.

Xiao Yan Xu, Avraham Klein, Kai Sun, Andrey V. Chubukov, Zi Yang Meng