Angular‐Resolved Magnetometry Beyond Triclinic Crystals Part II: Torque Magnetometry of Cp*ErCOT Single‐Molecule Magnets

Abstract

The experimental investigation of the molecular magnetic anisotropy in crystals in which the magnetic centers are symmetry related, but do not have a parallel orientation has been approached by using torque magnetometry. A single crystal of the orthorhombic organometallic Cp*ErCOT [Cp*=pentamethylcyclopentadiene anion (C5Me5(-)); COT=cyclooctatetraenedianion (C8H8(2-))] single-molecule magnet, characterized by the presence of two nonparallel families of molecules in the crystal, has been investigated above its blocking temperature. The results confirm an Ising-type anisotropy with the easy direction pointing along the pseudosymmetry axis of the complex, as previously suggested by out-of-equilibrium angular-resolved magnetometry. The use of torque magnetometry, not requiring the presence of magnetic hysteresis, proves to be even more powerful for these purposes than standard single-crystal magnetometry. Furthermore, exploiting the sensitivity and versatility of this technique, magnetic anisotropy has been investigated up to 150 K, providing additional information on the crystal-field splitting of the ground J multiplet of the Er(III) ion.

Diamondoid Structure in a Metal–Organic Framework of Fe4 Single‐Molecule Magnets

“…Otherwise, the overall magnetic response would also be tensorial in nature and isotropic in a plane orthogonal to a threefold or fourfold axis. This requires working at sufficiently low temperatures and/or in high applied fields, as firmly established by previous reports …”

Magnetic Anisotropy in Pentacoordinate NiII and CoII Complexes: Unraveling Electronic and Geometrical Contributions

“…This cannot be achieved by standard magnetometry because of the presence of more than one noncollinear susceptibility tensor in the unit cells. Cantilever torque magnetometry (CTM) has demonstrated a major ability to separate more than one contribution to the magnetic anisotropy coming from either intramolecular or intermolecular noncollinearity. More recently, the technique was also applied to magnetic metal–organic frameworks and anisotropic thin films .…”

Mapping the Magnetic Anisotropy inside a Ni4 Cubane Spin Cluster Using Polarized Neutron Diffraction

“…This, indeed, requires the presence of a strong uniaxial magnetic anisotropy and, hence, a good knowledge of the magneto-structural relationships at the molecular level [1,2] Side by side with numerous theoretical studies based on quantum calculations [3][4][5], such knowledge has been greatly improved by the use of experimental methods, such as electron paramagnetic resonance spectroscopy (EPR) [6] or, more recently, by angular-resolved or torque magnetometry [7,8]. The main difficulty with these methods is to access the local magnetic anisotropy even when performed on single crystals.…”