Free-standing magnetic nano-membranes for electron spin-filtering applications

TL;DR

This paper reports the fabrication and characterization of ultra-thin ferromagnetic nano-membranes that serve as efficient spin filters for electrons, with high figure of merit and potential for advanced electron spectroscopy applications.

Contribution

It demonstrates the successful fabrication of gold-capped Co nano-membranes below 10 nm thickness with high Sherman function and figure of merit, advancing spin-filter technology.

Findings

Sherman function of approximately 0.41

Transmission rate of 3.7×10⁻² at 2 eV

Highest reported 2D figure of merit of 67.2

Abstract

Free-standing ferromagnetic nano-membranes with thicknesses below 10 nm could effectively be used for spin selective filtering of electrons. Such membranes can work both as spin detectors in electron-spectroscopy, -microscopy and -diffraction as well as a source of spin polarized electrons. Theoretical studies and previous work has indicated that ferromagnetic membranes of a few nm have Sherman functions in the 30-60 % range and would provide an effective alternative to current spin detection technology. Here we demonstrate the fabrication of gold capped Co nano-membranes with a 2.6 nm Co layer and a total thickness below 10 nm. The membranes have a Sherman function $S\approx 0.41$ and a transmission of $3.7\times 10^{-2}$ for electron energies of 2 eV. The integration of such spin-filtering membranes in a hemispherical electron analyzer is shown to provide massively parallel detection capabilities and a "2-dimensional" figure of merit $FOM_\mathrm{2D}$ = 67.2, the highest reported to date.