Electrically controlled quantum transition to an anomalous metal in 2D

The mechanism through which superconductivity is destroyed upon controlled disordering often holds the key to understanding the mechanism of emergence of superconductivity. Here we demonstrate an $in$-$situ$ mechanism to control the fraction of disorder in a 2D superconductor. By controlling an electric field V$_G$, we created an assembly of segregated superconducting nano-islands and varied the inter-island distance to accomplish a quantum phase transition from a superconducting phase to a strange quantum anomalous metallic (QAM) phase at LaVO$_3$/SrTiO$_3$ interfaces. In the QAM phase, the resistivity dropped below a critical temperature (T$_{CM}$) as if the system was approaching superconductivity, and then saturated, indicating the destruction of global phase coherence and the emergence of a phase where metal-like transport of Bosons (a Bose metal) becomes a possibility. The unprecedented control over the island size is obtained through the control of nanometer scale ferroelectric domains formed in the SrTiO$_3$ side of the interface due to a low-temperature structural phase transition.