Pressure-induced superconducting-insulating phase transition in copper oxide superconductors
Abstract
<p indent="0mm">According to the band theory of solid-state physics, the electrical conductivity of solids is determined by their band structure. For insulators or semiconductors with an energy gap, the pressure-induced broadening of the bands can close the energy gap and lead the system to transfer into a normal metallic or superconducting ground state. This type of insulator-metal phase transition is known as the Wilson phase transition. However, a pressure-induced transition from the metallic or superconducting phase to the insulating phase is beyond the predictability of the classic theory. In this study, we primarily introduced the recent discovery of the pressure-induced, superconducting-insulating quantum phase transition (QPT) in hole-doped bismuth-based copper oxide high-temperature superconductors (HTSCs), and discussed and analyzed the universality of the QPT. This finding offers a new paradigm for generating exotic quantum states under pressure in strongly correlated electron systems, demonstrating the intrinsic connections between superconductivity and adjacent quantum states. Moreover, it provides new experimental evidence for a deeper understanding of the relationship between the superconducting state and other quantum states in strongly correlated electron systems. Furthermore, we analyzed the universality of this superconducting-insulating QPT and proposed some important issues for future research, aiming to provide useful information for further elucidating the underlying mechanism of HTSC.</p>
