# Non-local spin valve interferometer: Observation of superconducting spin current and Aharonov-Anandan's non-adiabatic geometric phase

## TL;DR

This paper reports the experimental observation of superconducting spin current and non-adiabatic geometric phase using a non-local spin valve interferometer with a ring-shaped normal metal, revealing new insights into spin transport and quantum phases.

## Contribution

It demonstrates the first experimental observation of Aharonov-Anandan's non-adiabatic geometric phase in a spin interferometer and challenges existing theories on superconducting spin resistance.

## Key findings

- High spin signal of 200 mΩ observed
- Identification of non-adiabatic geometric phase in spin precession
- Spin resistance in superconducting Aluminum matches normal state

## Abstract

An electron interferometer was designed and fabricated via a normal metal/insulator/ferromagnet non-local lateral spin valve with a ring-shaped normal metal/insulator spacer, and spin current interference was observed. A very high spin signal of 200 m$\Omega$ was found in a device with 2 $\mu$m injector-detector distance and magnetic field swept parallel to the plane. With a perpendicular magnetic field sweep, a Hanle effect measurement showed both spin precession and $h/e$ oscillation. Because of the non-adiabatic nature of the precessing spins at low fields as they traverse the normal metal ring, this is an experimental observation of Aharonov-Anandan's non-adiabatic geometric phase. In addition, our observation of identical spin resistance for normal and superconducting Aluminum is inconsistent with theoretical predictions based on the quasiparticle picture. To explain the superconducting spin current we suggest that spin triplet Cooper pairs may exist in thin films of Aluminum for direct spin injection.