Unconventional superconductivity in $A$V${}_2{X}_2$O family of surface altermagnets

Abstract

Motivated by the recent discovery of superconductivity at 16.3 K in layered oxychalcogenide Na${}_{2-x}$V${}_2$Se${}_2$O we investigate pairing instabilities in the broader family of layered materials composed of V${}_2$O planes, believed to exhibit altermagnetic order in their monolayer form. Even though the bulk family members KV${}_2$Se${}_2$O and Rb${}_{1-\hat{I}´}$V${}_2$Te${}_2$O are likely conventional antiferromagnets that show only surface altermagnetism, our analysis predicts exotic equal-spin triplet superconductivity as the dominant pairing instability in these materials. This is a consequence of their unique magnetic and sublattice structure that renders electron bands incompatible with conventional spin-singlet pairing. The predicted triplet superconducting phases are topologically non-trivial and capable of supporting spin-polarized persistent currents, properties potentially useful in technological applications.

4 pages, 3 figures + short SM