High pressure effects in fluorinated HgBa2Ca2Cu3O(8+d)

TL;DR

This study investigates how applying high pressure affects the superconducting transition temperature (Tc) in fluorinated HgBa2Ca2Cu3O(8+d) ceramics, revealing pressure-induced Tc enhancement and a record Tc of 166 K.

Contribution

It demonstrates that pressure can significantly increase Tc in fluorinated Hg-1223, achieving a new record, and highlights the role of lattice compression in Tc enhancement.

Findings

Tc increases with pressure up to a maximum and then decreases.

A record Tc of 166 K was achieved at 23 GPa.

Fluorine doping decreases the a-parameter, aiding Tc increase.

Abstract

We have measured the pressure sensitivity of Tc in fluorinated HgBa2Ca2Cu3O(8+d) (Hg-1223) ceramic samples with different F contents, applying pressures up to 30 GPa. We obtained that Tc increases with increasing pressure, reaching different maximum values, depending on the F doping level, and decreases for a further increase of pressure. A new high Tc record (166 K +/- 1 K) was achieved by applying pressure (23 GPa) in a fluorinated Hg-1223 sample near the optimum doping level. Our results show that all our samples are at the optimal doping, and that fluorine incorporation decreases the crystallographic $a$-parameter concomitantly increasing the maximum attainable Tc. This effect reveals that the compression of the $a$ axes is one of the keys that controls the Tc of high temperature superconductors.