Magnetic Coupling ofGd3N@C80Endohedral Fullerenes to a Substrate

Abstract

Using magnetic endohedral fullerenes for molecular spintronics requires control over their encapsulated magnetic moments. We show by field-dependent x-ray magnetic circular dichroism measurements of Gd3N@C80 endohedral fullerenes adsorbed on a Cu surface that the magnetic moments of the encapsulated Gd atoms lie in a 4f7 ground state and couple ferromagnetically to each other. When the molecules are in contact with a ferromagnetic Ni substrate, we detect two different Gd species. The more abundant one couples antiferromagnetically to the Ni, whereas the other one exhibits a stronger and ferromagnetic coupling to the substrate. Both of these couplings to the substrate can be explained by an indirect exchange mechanism mediated by the carbon cage. The origin of the distinctly different behavior may be attributed to different orientations and thus electronic coupling of the carbon cage to the substrate, as revealed by scanning tunneling microscopy of the fullerenes on Cu.

Exchange Interaction of Strongly Anisotropic Tripodal Erbium Single-Ion Magnets with Metallic Surfaces

“…The experimentally observed exchange energy of Er(trensal) is 1 order of magnitude smaller than the exchange energy found in TbPc 2 double deckers deposited on the same ferromagnetic out-of-plane Ni/ Cu(100) substrate 31 and almost 2 orders of magnitude smaller than the exchange energy obtained for Feporphyrins on the same type of substrate (17 meV). 46 In a very recent study on Gd 3 N@C 80 endofullerenes, also on Ni/Cu(100), the coexistence of antiferromagnetically and ferromagnetically coupled species was found with coupling strengths j in the order of a few meV 47 giving an estimated exchange energy of E ex = 10À 40 meV. These observations follow the trend that the magnetic exchange coupling between 3d and 4f magnetic moments is weaker than the 3dÀ3d coupling because of the localized nature of the 4f shell.…”

The UE46 PGM-1 beamline at BESSY II

“…• Charge order of high-Tc Superconductors (Blanco-Canosa et al, 2013;Comin et al, 2014;da Silva Neto et al, 2014;Fink et al, 2009;Ghiringhelli et al, 2012) • Coupling of electronic / lattice degrees of freedom in multiferroic materials (Glavic et al, 2013;Partzsch et al, 2011;Schierle et al, 2010;Schmitz-Antoniak et al, 2013;Skaugen et al, 2015) • Microcrystals of novel materials (Leininger et al, 2011;Matsuda et al, 2015) • Interfacial electronic properties in heterostructures (Frano et al, 2013;Wadati et al, 2009) • Element-speci c magnetic hysteresis loops (Radu et al, 2012) • Single molecular magnets (Bernien et al, 2015;Hermanns et al, 2013) • Electronic depth pro les • Electronic ground states and phase transitions in correlated materials (Schmitz et al, 2014;Strigari et al, 2013;Willers et al, 2012Willers et al, , 2011 • Magnetic clusters in carbon nanotubes (Shiozawa et al, 2015) • Nanoparticles for medical applications (Graf et al, 2015) • Magnetic semiconductors (Khalid et al, 2014) …”

Molecular lanthanide single-ion magnets: from bulk to submonolayers

“…Although reports on single-ion magnetic species adsorbed on surfaces are still lacking, experiments have been performed with the structurally similar polynuclear species Dy 3 N@C 80 [118], Dy 2 ScN@C 80 [182] and Gd 3 N@C 80 [119]. Nevertheless, work on these species will be briefly reviewed here because their structure is closely related to the corresponding SIMs such as DySc 2 N@C 80 [114].…”

“…In contrast to all other SIMs discussed in this review, endohedral metallofullerenes are not synthesized via conventional coordination chemistry approaches but by an arc discharge technique [113]. Slow relaxation in the endohedral metallofullerenes DySc 2 N@C 80 and HoSc 2 N@C 80 has been reported [114][115][116][117], with magnetization relaxation times of DySc 2 N@C 80 exceeding several hours at 2 K. Since these molecules can be sublimed in UHV [118,119] they are appealing candidates for surface studies alike the other two families of SIMs mentioned before. The molecular structure obtained from density-functional theory (DFT) geometry optimization is shown in figure 9 along with the magnetic hysteresis observed on DySc 2 N@C 80 .…”