# Spin and Momentum Mapping of Highly Oriented Spinterfaces

## TL;DR

This paper explores how molecular order at magnetic interfaces affects electron spin properties, revealing new insights for designing spin-functional devices.

## Contribution

The study demonstrates that long-range molecular order enables coherent Umklapp scattering of spin-polarized electrons at spinterfaces.

## Key findings

- Both FePc and H2Pc monolayers generate distinct Umklapp replicas of the substrate valence bands.
- Spin polarization near normal emission is mainly due to scattering, not direct molecular orbital contributions.

## Abstract

Structurally defined
interfaces between magnetic substrates and
molecular layers, so-called spinterfaces, represent
a critical frontier in the design of spin-functional devices. Here,
we show that long-range molecular order enables coherent Umklapp scattering
of spin-polarized substrate electrons, modifying the spin-resolved
electronic structure at the interface. Using spin-resolved momentum
microscopy and photoemission tomography, we compare iron (FePc) and
metal-free phthalocyanine (H2Pc) monolayers assembled on
an oxygen-passivated iron surface. We find that both molecular lattices
give rise to distinct Umklapp replicas of the substrate valence bands.
By selectively probing the momentum space, we demonstrate that spin
polarization near normal emission is predominantly governed by scattering
rather than direct contributions from possibly spin-polarized molecular
orbitals. This work underscores the intricate relationship between
structural order and spin functionality, providing valuable insights
into engineering spinterfaces.