Circular dichroism and angular deviation in x-ray absorption spectra of Dy2ScN@C80 single-molecule magnets on h−BN/

Abstract

Endohedral fullerenes, such as Dy 2 ScN@C 80 , are single-molecule magnets with long relaxation times of their magnetization. An open and anisotropic 4f electron shell in the lanthanides (here Dy) imposes a magnetic moment that maintains its orientation at liquid-helium temperatures for macroscopic times. If these molecules shall be used as single-bit information storage elements or for quantum operations, the orientation of the endohedral units and the orientation of the magnetic moments has to be controlled. X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD)-with variation of the angle of x-ray incidenceallows for the detection of these two structural elements. We present XMCD data of Dy 2 ScN@C 80 on an h-BN/Rh(111) nanomesh that display at 2 K a large hysteresis with a coercive field of 0.4 T. The angular dependence of the XAS data at the Dy M 5 edge indicates partial ordering of the endohedral units. In order to quantify anisotropic orientation we introduce the "deviation" D as an operational quantity that measures differences between two spectra.

Substrate‐Independent Magnetic Bistability in Monolayers of the Single‐Molecule Magnet Dy2ScN@C80 on Metals and Insulators

“…However, magnetic hysteresis of the monolayer was considerably narrower than for a multilayer sample. A broader hysteresis than on Rh(111) was observed for Dy 2 ScN@C 80 on h ‐BN|Rh(111) . Here we demonstrate that the SMM properties of Dy 2 ScN@C 80 monolayers on Au(111) and Ag(100), as well on a thin film of insulator MgO grown on Ag(100), do not depend on the substrate, which highlights the robustness of fullerene SMMs and the protective function of the carbon cage.…”

Attaining record-high magnetic exchange, magnetic anisotropy and blocking barriers in dilanthanofullerenes

“…[22][23][24] However, obtaining a large exchange coupling between two Ln 3+ metal ions is a formidable task as 4f orbitals are deeply buried, leading to a weak/no interaction in dinuclear or polynuclear Ln 3+ complexes. 8,[25][26][27][28][29][30] In this regard, lanthanide encapsulated fullerenes (called endohedral metallofullerenes or EMFs) are gaining tremendous attention for various reasons (a) they offer stability to the guest molecules which are otherwise unstable 31 (b) thanks to their strong  cloud, fabrication of such molecules on Graphene/HOPG/CNTs and other surfaces are straightforward [31][32][33][34][35][36][37][38][39] (c) during this process the guest molecules stay intact, and hence they are unlikely to lose their characteristics upon fabrication 31 (d) as fullerenes are made of pure carbon, and the source of nuclear spin of the guest molecules can be controlled, they offer a nuclear spin free systems -a key criterion for some Q-bits applications. 31,40 These key advantages mentioned here directly address the aforementioned goals (ii) and (iii), making them superior to traditional coordination chemistry/organometallic SMMs/SIMs.…”

Sub-Kelvin hysteresis of the dilanthanide single-molecule magnet Tb2ScN@C80

“…Figure 1 (b) shows the model of the ground state of Tb 2 ScN@C 80 in zero external magnetic field. The two paramagnetic Tb 3+ ions in the Tb 2 ScN endohedral unit In the center the of the Tb 3+ ions (turquois) the 4f (Jz = 6) orbitals that constitute the paramagnetism are depicted in red [17,18]. (b) Magnetic zero field ground states: The magnetic moments µ of the two Tb ions sit on an equilateral triangle and point into the center or away from it.…”