High-Pressure Synthesis of Calcium-Free Double-Layered Cuprate Superconductors with Critical Temperature above 100 K

Abstract

This study reviews newly discovered high-temperature cuprate superconductors synthesized using high-pressure techniques. These materials feature double CuO₂ planes separated by Sr within their blocking layers, with Sr also serving as the principal element comprising the blocking layers. Previously, CuO₂ planes in cuprate superconductors with critical temperatures (T_c) exceeding 100 K were invariably separated by Ca. Remarkably, some of these new cuprates, such as (Hg,Re)Sr₂SrCu₂O_y, Sr₂SrCu₂O_4+yF_2-y, achieve a T_c in the 100 K range despite the absence of Ca in their chemical composition. This discovery underscores the potential for further exploration of new cuprate superconductors through the application of high-pressure synthesis techniques.