Roland Stania
August 2(Tue) - August 2(Tue), 2016
Conformational changes in TbSc2N@C80 on h-BN/Ni(111)
Roland Stania
University of Zurich
Fullerene carbon cages encapsulating nitride complexes with lanthanides [1] belong to the so-called endofullerene class. They show strong magnetic behavior and may act as single molecular magnets (SMM) with long relaxation times [2]. When adsorbed on
insulating surfaces, they can form well ordered single-layer domains [3] with multiple possible conformations.
We performed high resolution x-ray photoelectron di raction (XPD) at the PEARL beamline [4] of the swiss light source to distinguish the di erent conformations for the case of TbSc2N@C80 adsorbed on a single layer of hexagonal boron nitride (h-BN) on Ni(111). Three di erent con gurations can be identi ed and veri ed via a combination of di erent surface science techniques. TbSc2N@C80 forms, under good growth conditions, single layers of well ordered domains. The degrees of freedom of the endohedral unit and the C80 cage are independent of each other and the onset of their motion is clearly distinguishable. While the C80 cage is found to be in rotational motion around the z-axis at room temperature, it freezes
around T = 230 K, with the endohedral unit remaining in a rotation-like hopping motion along the atoms of the hexagon-pentagon borders of the carbon cage - and only freezes to immobility below T = 70 K. The rotational onset of the endohedral unit additionally enforces a work function change of the entire SMM between T = 70 K and T = 150 K.
References
[1] S. Stevenson, et al., Nature 401 (1999), 55-57
[2] R. Westerstrom, et al., J. Am. Chem. Soc 134 (2012), 134
[3] C. Norenberg, et al., Journal of Physics: Conference Series 100 (2008), 052080
[4] M. Muntwiler, et al., submitted