Surface Aligned Magnetic Moments and Hysteresis of an Endohedral Single-Molecule Magnet on a Metal

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 4f 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 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 ∼4 K. From the measured hysteresis curves, we estimate the zero field remanence lifetime during x-ray exposure of a submonolayer to be about 30 seconds.

Mononuclear Clusterfullerene Single‐Molecule Magnet Containing Strained Fused‐Pentagons Stabilized by a Nearly Linear Metal Cyanide Cluster

“…Figure 3 A shows the normalized magnetizations of TbNC@C 76 versus the applied field‐temperature quotient x =μ 0 H/T measured at seven temperatures between 1.8 and 10 K. The good scaling in this temperature range indicates that the ligand field, which splits the Hund ground state, is so strong that the low temperature magnetization may be described with one J z level. Based on a perfect fit between the experimental magnetization data and the non‐collinear magnetic moment model proposed previously for Dy x Sc 3− x N@C 80 ,9a–9c the magnetic moment | μ | of TbNC@C 76 is determined to be 8.9 μ B , which agrees well with the theoretical limit of 9 μ B . Therefore, the Tb ground state is assigned to be J z =±6 (see Supporting Information S7).…”

Endohedral Clusterfullerenes: Future Perspectives

“…Very recently, owing to their relatively long magnetic relaxation times (See Figure 3), the mixed-metal nitride clusterfullerenes Dy x Sc 3-x N@C 80 (x = 1-3) have received attention in the field of single-molecule magnets (SMM). [27][28][29] These compounds might find use in novel SMM based memory devices. Popov and co-workers found that a new type of μ 3 -C mixed-metal carbide clusterfullerene, Dy 2 TiC@I h -C 80, also exhibits SMM behavior.…”

4f occupancy and magnetism of rare-earth atoms adsorbed on metal substrates

“…In addition, the XMCD sum rules [38,39] and multiplet analysis can be used to estimate the corresponding J z values. We chose late lanthanides for their large magnetic moments coming from the parallel alignment of L and S. Additionally, they exhibit larger magnetic anisotropy and have been more intensively studied as model systems for atomic magnetic memories in single ion [40][41][42][43] and single atom magnets [17,18]. Among the series of late lanthanides, we investigated Dy, Ho, Er, and Tm as they have been found both in divalent and trivalent states in bulk compounds [44], hence, they represent ideal candidates to explore the interplay between surface binding, 4f occupancy, and strength of the crystal field.…”