Quantum Melting of a Two-Dimensional Vortex Lattice at Zero Temperature

We consider the quantum melting of a two-dimensional flux lattice at temperature T = 0 in the ``superclean limit.'' In this regime, we find that vortex motion is dominated by the Magnus force. A Lindemann criterion predicts melting when $n_v/n_p \geq \beta$, where $n_v$ and $n_p$ are the areal number densities of vortex pancakes and Cooper pairs, and $\beta \approx 0.1$. A second criterion is derived by using Wigner crystal and Laughlin wave functions for the solid and liquid phases respectively, and setting the two energies equal. This gives a melting value similar to the Lindemann result. We discuss the numerical value of the melting field at $T = 0$ for thin layers of low-T$_c$ superconductor, such as $a-MoGe$, and single layers of high-T$_c$ materials.