Robust Single Molecule Magnet Monolayers on Graphene and Graphite with Magnetic Hysteresis up to 28 K

Abstract

The chemical functionalization of fullerene single molecule magnet Tb2@C80(CH2Ph) enables the facile preparation of robust monolayers on graphene and highly oriented pyrolytic graphite from solution without impairing their magnetic properties. Monolayers of endohedral fullerene functionalized with pyrene exhibit magnetic bistability up to a temperature of 28 K. The use of pyrene terminated linker molecules opens the way to devise integration of spin carrying units encapsulated by fullerene cages on graphitic substrates, be it single‐molecule magnets or qubit candidates.

Electrophilic Trifluoromethylation of Dimetallofullerene Anions en Route to Air-Stable Single-Molecule Magnets with High Blocking Temperature of Magnetization

“…8,24,25 In particular, Tb 2 @ C 80 (CH 2 Ph) was found to be a single-molecule magnet (SMM, see refs 26−28 for recent reviews) with extremely broad magnetic hysteresis and blocking temperature of magnetization near 30 K, 8,29 which made it one of the strongest SMMs second to only some Dy and Tb lanthanocenes. 30−33 Furthermore, Tb 2 @C 80 (CH 2 Ph) and its pyrrolidine cycloadduct 29 show the highest hysteresis temperature and the longest relaxation times among air-stable SMMs 34−38 and self-assembled monolayers of Tb 2 @ C 80 (CH 2 Ph) derivative on graphene and graphite exhibit magnetic hysteresis up to 28 K. 29 Despite this success, the benzylation route revealed some drawbacks, making it far from being optimal when the upscale of the di-EMF production is required. Monometallofullerenes (mono-EMFs), which are produced in the arc-discharge process in a considerably higher yield than di-EMFs, are also extracted by DMF as anions and benzylated by CH 2 PhBr with formation of many regioisomers.…”

The Role of Radical Bridges in Polynuclear Single‐Molecule Magnets

“…The exchange coupling can be enhanced through a covalent metal‐metal bond, which has been shown in several dimetallofullerenes (di‐EMFs) [21–30] . Among all di‐EMFs, monolayers of Tb 2 @C 80 (CH 2 Ph) have shown the highest blocking temperature of 28 K [31] …”

“…[20] The exchange coupling can be enhanced through a covalent metal-metal bond, which has been shown in several dimetallofullerenes (di-EMFs). [21][22][23][24][25][26][27][28][29][30] Among all di-EMFs, monolayers of Tb 2 @C 80 (CH 2 Ph) have shown the highest blocking temperature of 28 K. [31] On the other hand, the exchange coupling can be promoted through a radical ligand bridging Ln ions. There are several radical-bridged dilanthanide complexes showing notable SMM behavior.…”

Metamagnetic transition and a loss of magnetic hysteresis caused by electron trapping in monolayers of single-molecule magnet Tb2@C79N

“…[56][57][58][59][60][61][62] The nitride clusterfullerenes Dy 2 ScN@C 80 and DySc 2 N@C 80 were shown to maintain their SMM properties in monolayers on metallic substrates. [56][57][58][59][60] _ENREF_71_ENREF_73 Even more promising are recent studies of Dy 2 @C 80 (CH 2 Ph) deposited onto graphene 61 and Tb 2 @C 80 (CH 2 Ph) on graphene and HOPG, 62 which demonstrated that dimetallofullerenes with single-electron lanthanidelanthanide bonds can also sustain their superb SMM performance in monolayers. Magnetic hysteresis in these monolayers was observed at considerably higher temperatures than in all other surface-supported SMMs, reaching 28 K for a self-assembled monolayer of Tb 2 @C 80 (CH 2 Ph) derivative.…”

“…Magnetic hysteresis in these monolayers was observed at considerably higher temperatures than in all other surface-supported SMMs, reaching 28 K for a self-assembled monolayer of Tb 2 @C 80 (CH 2 Ph) derivative. 62 Unlike M 2 @C 80 (CH 2 Ph) derivatives, Tb 2 @C 79 N is free from exohedral organic group, which makes it sufficiently thermally stable for the growth of thin films by sublimation in ultrahigh-vacuum conditions. In this work, we report on the deposition of submonolayers of Tb 2 @C 79 N onto Au (111) and Cu (111) substrates and the electronic and magnetic properties thereof studied by scanning-tunneling microscopy, DFT calculations, and synchrotron-based X-ray absorption spectroscopy (XAS).…”