Comment on "Superconductivity and Mott Physics in Organic Charge Transfer Materials"

Menke et al. recently claimed that superconductivity (SC) in the $\kappa$-phase organic charge-transfer solids (CTS) can be understood within the two-dimensional half-filled anisotropic triangular-lattice Hubbard model. Experimentally, $\kappa$-CTS are mostly but not always antiferromagnetic (AFM) at ambient pressure and SC appears under pressure. In apparent agreement with this observation, Menke et al. found AFM ground states for small $t/U$ and SC over a small region at the interface of AFM and Fermi liquid ground states with increasing $t/U$ at fixed $t'/t$, where $U$ is the Hubbard repulsion. Menke et al's computational results directly contradict those obtained using exact diagonalization and Path Integral Renormalization Group approaches. It is clearly of interest to determine the origin of this discrepancy, especially in view of the facts that (a) related arguments continue to persist in the context of cuprate SC superconductivity (which however involves doping), and (b) there exist CTS in which SC is not proximate to AFM, but is separated by an intermediate charge-disproportionated phase. Here we show that Menke et al's conclusion regarding SC is incorrect and originates from a flawed assumption.