# Adsorption-Induced Surface Magnetism

## TL;DR

This study shows how adsorbing certain molecules on a copper surface can create magnetism, offering new ways to design spin-polarized states in hybrid materials.

## Contribution

The paper introduces a novel mechanism for inducing surface magnetism through molecular adsorption without using magnetic materials.

## Key findings

- Spin-polarized states form on Cu(100) when TO[11]H molecules are adsorbed.
- Strong chemisorption and hybridization between molecular and copper states drive spin polarization.
- A modified theoretical model explains the threshold for spin polarization emergence.

## Abstract

We report the emergence
of adsorption-induced magnetism
from heterohelicene
molecules on a nonmagnetic Cu(100) surface. Spin-polarized low-energy
electron microscopy measurements reveal spin-dependent electron reflectivity
for enantiopure 7,12,17-trioxa[11]­helicene (TO[11]­H) monolayers, indicating
the formation of a spin-polarized state localized in the topmost copper
layer. Control experiments on clean Cu(100) and TO[11]H on highly
oriented pyrolytic graphite show no such effect, excluding artifacts
and chirality-induced spin selectivity as origins. Spin-polarized
density functional theory calculations with hybrid functionals attribute
the magnetism to strong chemisorption, which induces hybridization
between the molecular HOMO and copper s- and d-states, driving asymmetric
spin-polarized charge redistribution at the interface. An extended
Newns–Anderson–Grimley model incorporating on-site Coulomb
repulsion in Cu d-orbitals reproduces the emergence of interfacial
spin polarization above a threshold interaction strength, highlighting
the key roles of hybridization parameters and Coulomb correlation.
These findings reveal a mechanism for inducing magnetism at molecule–metal
interfaces without inherently magnetic components, offering avenues
for engineering spin-polarized states in organic–inorganic
hybrid systems.