Observation of half-height magnetization steps in Sr2RuO4

TL;DR

This study reports the observation of half-height magnetization steps in Sr2RuO4, providing evidence for half-quantum vortices in this spin-triplet superconductor through cantilever magnetometry on mesoscopic samples.

Contribution

First direct experimental evidence of half-quantum vortices in Sr2RuO4 using magnetometry on mesoscopic samples.

Findings

Observation of half-integer magnetization steps.

Confirmation of half-quantum vortices in Sr2RuO4.

Detection of transitions between fluxoid states.

Abstract

Spin-triplet superfluids can support exotic objects, such as half-quantum vortices characterized by the nontrivial winding of the spin structure. We present cantilever magnetometry measurements performed on mesoscopic samples of Sr2RuO4, a spin-triplet superconductor. For micron-sized annular-shaped samples, we observe transitions between integer fluxoid states, as well as a regime characterized by "half-integer transitions," i.e., steps in the magnetization with half the height of the ones we observe between integer fluxoid states. These half-height steps are consistent with the existence of half-quantum vortices in superconducting Sr2RuO4.