Single-Molecule Magnets DyM N@C and Dy MN@C (M=Sc, Lu): The Impact of Diamagnetic Metals on Dy Magnetic Anisotropy, Dy⋅⋅⋅Dy Coupling, and Mixing of Molecular and Lattice Vibrations.

The substitution of scandium in fullerene single-molecule magnets (SMMs) DySc N@C and Dy ScN@C by lutetium has been studied to explore the influence of the diamagnetic metal on the SMM performance of dysprosium nitride clusterfullerenes. The use of lutetium led to an improved SMM performance of DyLu N@C , which shows a higher blocking temperature of magnetization (T =9.5 K), longer relaxation times, and broader hysteresis than DySc N@C (T =6.

Partial magnetic ordering in one-dimensional arrays of endofullerene single-molecule magnet peapods.

The magnetic ordering and bistability of one-dimensional chains of endofullerene Dy2ScN@C80 single-molecule magnets (SMMs) packed inside single-walled carbon nanotubes (SWCNTs) have been studied using high-resolution transmission electron microscopy (HRTEM), X-ray magnetic circular dichroism (XMCD), and ab initio calculations. X-ray absorption measurements reveal that the orientation of the encapsulated endofullerenes differs from the isotropic distribution in the bulk sample, indicating a partial ordering of the endofullerenes inside the SWCNTs. The effect of the one-dimensional packing was further investigated by ab initio calculations, demonstrating that for specific tube diameters, the encapsulation is leading to energetically preferential orientations of the endohedral clusters.

Strong carbon cage influence on the single molecule magnetism in Dy-Sc nitride clusterfullerenes.

Magnetic properties of endohedral metallofullerenes with nitride clusters DySc2N and Dy2ScN and different carbon cages are studied by SQUID magnetometry. All molecules behave as single molecule magnets (SMMs) and exhibit magnetic hysteresis. It is found that the blocking temperature of magnetization and relaxation times strongly depend on the fullerene cage, with the C80-Ih isomer offering the best SMM properties.

Nanoscale x-ray investigation of magnetic metallofullerene peapods.

Endohedral lanthanide ions packed inside carbon nanotubes (CNTs) in a one-dimensional assembly have been studied with a combination of high resolution transmission electron microscopy (HRTEM), scanning transmission x-ray microscopy (STXM), and x-ray magnetic circular dichroism (XMCD). By correlating HRTEM and STXM images we show that structures down to 30 nm are resolved with chemical contrast and record x-ray absorption spectra from endohedral lanthanide ions embedded in individual nanoscale CNT bundles. XMCD measurements of an ErN@C bulk sample and a macroscopic assembly of filled CNTs indicate that the magnetic properties of the endohedral Er ions are unchanged when encapsulated in CNTs.

Methane as a Selectivity Booster in the Arc-Discharge Synthesis of Endohedral Fullerenes: Selective Synthesis of the Single-Molecule Magnet Dy2TiC@C80 and Its Congener Dy2TiC2@C80.

The use of methane as a reactive gas dramatically increases the selectivity of the arc-discharge synthesis of M-Ti-carbide clusterfullerenes (M=Y, Nd, Gd, Dy, Er, Lu). Optimization of the process parameters allows the synthesis of Dy2TiC@C80-I and its facile isolation in a single chromatographic step. A new type of cluster with an endohedral acetylide unit, M2TiC2@C80, is discovered along with the second isomer of M2TiC@C80.