Topologically protected surface Majorana arcs and bulk Weyl fermions in ferromagnetic superconductors

TL;DR

This paper predicts that ferromagnetic superconductors with equal spin pairing support topologically protected surface Majorana arcs and bulk Weyl fermions, which can be experimentally observed using ARPES and STM techniques.

Contribution

It demonstrates that these three-dimensional ferromagnetic superconductors inherently support topologically protected quasiparticles like Majorana arcs and Weyl fermions.

Findings

Presence of topologically protected surface Majorana arcs.

Existence of bulk Weyl fermions as gapless excitations.

Potential observation via ARPES and STM experiments.

Abstract

A number of ferromagnetic superconductors have been recently discovered which are believed to be in the so-called "equal spin pairing" (ESP) state. In the ESP state the Cooper pairs condense forming order parameters $\Delta_{\uparrow\uparrow}, \Delta_{\downarrow\downarrow}$ which are decoupled in the spin-sector. We show that these three-dimensional systems should generically support topologically protected surface Majorana arcs and bulk Weyl fermions as gapless excitations. Similar protected low-energy exotic quasiparticles should also appear in the recently discovered non-centrosymmteric superconductors in the presence of a Zeeman field. The protected surface arcs can be probed by angle-resolved photoemission (ARPES) as well as scanning tunneling microscope (STM) experiments.