Metal-insulator transition and possible superconductivity in Pb_2.2Cu_0.8Sr_3.1La_1.5Cu_1.5O_y with hexagonal structure

Abstract

A metal-insulator transition and possible superconductivity has been found in Pb_2.2Cu_0.8Sr_3.1La_1.5 Cu_1.5O_y. The structure of this compound belongs to the hexagonal symmetry with the attice parameter a=10.11 Å, c=3.56 Å and space group P62 m. In this structure, there are not the traditional square CuO₂ planes as known in most cuprate superconductors. The parent compound of this phase is Pb₃Sr₅CuO₁₂(3501) which is an isolator. By replacing Pb and Sr with Cu and La, respectively, a metal-insulator transition and strong structural modulations occur in this material.

Key words:

• Metal-insulator transition
• Hexagonal superconducting phase
• Pb_2.2Cu_0.8Sr_3.1La_1.5Cu_1.5O_y