Tuning odd triplet superconductivity by spin pumping

TL;DR

This paper investigates how spin pumping from a precessing ferromagnet can tune odd-frequency superconductivity in a normal metal, revealing a crossover from even- to odd-frequency pairing observable via tunneling spectroscopy.

Contribution

It demonstrates the control of odd-frequency pairing through spin pumping frequency, providing a new way to manipulate superconducting states in hybrid structures.

Findings

Odd-frequency pairing is enhanced at twice the superconducting gap frequency.

A crossover from even- to odd-frequency superconductivity is achieved by tuning precessional frequency.

Observable signatures include a transition from gap to peak structures in tunneling conductance.

Abstract

We study proximity effect in diffusive ferromagnet/normal-metal/superconductor junction with precessing magnetization of the ferromagnet. We find that the odd-frequency pairing induced in the normal metal is modified by spin pumping from the ferromagnet and hence can be tuned by changing the precessional frequency. At the frequency corresponding to twice the superconducting gap, the odd-frequency pairing is strongly enhanced. We find a crossover from the even- to the odd-frequency superconductivity in the normal metal by tuning the precessional frequency. This gives a clearcut signature of the odd-frequency superconductivity observable by scanning tunneling microscopy. According to the pairing symmetries in the normal metal, we find a crossover from the gap to the peak structure in the tunneling conductance between the normal metal and a scanning tunneling microscope tip.