Evidence of superconductivity on the border of quasi-2D ferromagnetism in Ca2RuO4 at high pressure

TL;DR

This study provides evidence that Ca2RuO4 exhibits weak superconductivity near a quasi-2D ferromagnetic phase under high pressure, revealing a complex interplay between magnetism and superconductivity.

Contribution

The paper reports the discovery of superconductivity in Ca2RuO4 at high pressure, near the boundary of quasi-2D ferromagnetism, which was not previously known.

Findings

Superconductivity observed at pressures above 90 kbar.

Resistivity and ac susceptibility show downturns below 0.4 K.

Superconductivity occurs near the boundary of ferromagnetic order.

Abstract

The layered perovskite Ca2RuO4 is a spin-one Mott insulator at ambient pressure and exhibits metallic ferromagnetism at least up to ~ 80 kbar with a maximum Curie temperature of 28 K. Above ~ 90 kbar and up to 140 kbar, the highest pressure reached, the resistivity and ac susceptibility show pronounced downturns below ~ 0.4 K in applied magnetic fields of up to ~10 mT. This indicates that our specimens of Ca2RuO4 are weakly superconducting on the border of a quasi-2D ferromagnetic state.