Quantum Criticality in the Two-Dimensional Periodic Anderson Model

Despite the fascinating phenomena accompanying a quantum critical point, e.g. non-Fermi liquid behavior, a general theory for quantum phase transitions is lacking. In this talk, I will present a step forward by analyzing results from the dynamical vertex approximation, a cutting-edge quantum field theoretical method including temporal as well as spatial correlations. Within this framework, I will analyze the fundamental model of strongly correlated heavy fermion compounds, the periodic Anderson model. By varying the hybridization strength of localized f-electrons and itinerant d-electrons, and a careful analysis of response functions, one can trace the change in the ground state from an antiferromagnet to a paramagnetic Kondo insulating phase, resembling the famous Doniach phase diagram. Eventually, I will show the evolution of the critical exponents of the magnetic susceptibility, which are changing from the one of free spins γ=1 to γ=2 in the quantum critical regime. T. Schäfer, A. Katanin, K. Held, and A. Toschi, PRL 119, 046402 (2017), T. Schäfer, A. Katanin, M. Kitatani, A. Toschi, and K. Held, in preparation.