Surface aligned magnetic moments and hysteresis of an endohedral single-molecule magnet on a metal

TL;DR

This study investigates the magnetic orientation and hysteresis behavior of a Dy-based single-molecule magnet on a metal surface, revealing strong anisotropy and surface-induced alignment with implications for magnetic stability.

Contribution

It demonstrates surface-induced alignment of magnetic moments and characterizes hysteresis in a Dy-based single-molecule magnet on a metal substrate.

Findings

Dy 4f orbitals align parallel to the surface.

Strong magnetocrystalline anisotropy observed.

Hysteresis detected at 4 K with a 30-second remanence lifetime.

Abstract

The interaction between the endohedral unit in the single-molecule magnet Dy$_2$ScN@C$_{80}$ and a rhodium (111) substrate leads to alignment of the Dy 4$f$ orbitals. The resulting orientation of the Dy$_2$ScN plane parallel to the surface is inferred from comparison of the angular anisotropy of x-ray absorption spectra and multiplet calculations in the corresponding ligand field. The x-ray magnetic circular dichroism (XMCD) is also angle dependent and signals strong magnetocrystalline anisotropy. This directly relates geometric and magnetic structure. Element specific magnetization curves from different coverages exhibit hysteresis at a sample temperature of $\sim4$ K. From the measured hysteresis curves we estimate the zero field remanence life-time during x-ray exposure of a sub-monolayer to be about 30 seconds.