Interplay between superconductivity and ferromagnetism in crystalline nanowires

Microscopic theory for a ferromagnetic nanowire/superconductor heterostructure: Transport, fluctuations, and topological superconductivity

“…As we show in later parts of the paper, the treatment of the wire in this limit is reasonably justified based on experimental data 21 and past studies on Co band structure. [56][57][58][59] The information available to us is insufficient to determine the nature of proximity-induced superconductivity in the nanowire.…”

“…16 However, a number of recent experimental studies have demonstrated an unexpectedly long-ranged proximity effect in mesoscopic superconductor-ferromagnet hybrid structures. [17][18][19][20][21][22] There are a number of theoretical scenarios which can explain this phenomenon. In most of the scenarios pair correlations inside the ferromagnet are attributed to some type of equal-spin triplet pairing.…”

“…While the exact nature of the pairing symmetry still remains open, if the proximity effect can be attributed to triplet p-wave pairing, the experiment of the kind in Ref. 21 is very close to realizing a topological superconductor, 30 and can host the sought-after Majorana fermions at the two ends of the wire.…”

“…[46][47][48][49][50][51] However, Ref. 21 claims that the peaks observed in their experiment are distinct from those attributed to nonequilibrium charge imbalance [46][47][48][49] and spin accumulation 50,51 effects. This invites a search for an alternative mechanism behind the resistance peak.…”

“…However, the cobalt wire studied in Ref. 21 is single domain so such inhomogeneities may not be the mechanism behind the singlet-triplet conversion. In a 1D junction, long-ranged proximity effect of singlet pairs are possible in a clean ferromagnet due to the absence of destructive interference among various transverse channels which usually lead to their short-ranged proximity effect in higher dimensions.…”