# Magnetic properties of Dy nano-islands on graphene

## TL;DR

This study investigates the magnetic properties of dysprosium nano-islands on graphene, revealing temperature-dependent magnetic behavior distinct from bulk Dy, with implications for nanoscale magnetic material applications.

## Contribution

First detailed XMCD analysis of Dy nano-islands on graphene showing unique magnetic temperature dependence compared to bulk Dy.

## Key findings

- Magnetic moment projection of 3.5 μ_B at 5 T and 15 K.
- Onset of magnetic moment change near 175 K, close to bulk Dy's helical transition.
- Inverse magnetic moment linear with temperature below 130 K, indicating paramagnetic behavior.

## Abstract

We have determined the magnetic properties of epitaxially grown Dy islands on graphene/SiC(0001) that are passivated by a gold film (deposited in the ultra-high vacuum growth chamber) for {\it ex-situ} X-ray magnetic circular dichroism (XMCD). Our sum-rule analysis of the Dy $M_{4,5}$ XMCD spectra at low temperatures ($T=15$ K) as a function of magnetic field assuming Dy$^{3+}$ (spin configuration $^6H_{15/2}$) indicate that the projection of the magnetic moment along an applied magnetic field of 5 T is 3.5(3) $\mu_B$. Temperature dependence of the magnetic moment (extracted from the $M_5$ XMCD spectra) shows an onset of a change in magnetic moment at about 175 K in proximity of the transition from paramagnetic to helical magnetic structure at $T_{\rm H} =179$ K in bulk Dy. No feature at the vicinity of the ferromagnetic transition of hcp bulk Dy at $T_{\rm c}$ = 88 K is observed. However, below $\sim$130 K, the inverse magnetic moment (extracted from the XMCD) is linear in temperature as commonly expected from a paramagnetic system suggesting different behavior of Dy nano-island than bulk Dy.