Mott Quantum Criticality in the Anisotropic 2D Hubbard Model

We present evidence for Mott quantum criticality in an anisotropic two-dimensional system of coupled Hubbard chains at half-filling. In this scenario emerging from variational cluster approximation and cluster dynamical mean-field theory, the interchain hopping $t_{\perp }$ acts as a control parameter driving the second-order critical end point $T_c$ of the metal-insulator transition down to zero at $t_{\perp }^c\mathrm{/}t\simeq 0.2$. Below $t_{\perp }^c$, the volume of the hole and electron Fermi pockets of a compensated metal vanishes continuously at the Mott transition. Above $t_{\perp }^c$, the volume reduction of the pockets is cut off by a first-order transition. We discuss the relevance of our findings to a putative quantum critical point in layered organic conductors, whose location remains elusive so far.