Abstract
A homoleptic gadolinium(III) complex with the smallest helicene-type ligand, 1,10-phenanthroline-N,N′-dioxide (phendo) [Gd(phendo)4](NO3)3·xMeOH (phendo = 1,10-phenanthroline-N,N′-dioxide, MeOH = methanol), shows slow relaxation of the magnetization characteristic for Single Ion Magnets (SIM), despite negligible magnetic anisotropy, confirmed by ab initio calculations. Solid state dilution magnetic and EPR studies reveal that the magnetization dynamics of the [Gd(phendo)4]3+ cation is controlled mainly by a Raman process. Pulsed EPR experiments demonstrate long phase memory times (up to 2.7 μs at 5 K), enabling the detection of Rabi oscillations at 20 K, which confirms coherent control of its spin state.
Highlights
Single molecule magnets (SMMs) enjoy renewed interest in the field of molecular magnetism[1,2] due to a rapid increase of the magnetization blocking temperatures approaching the boiling point of nitrogen[3−5] and their implementation as molecular qubits
Rational tuning of the magnetic anisotropy by employing a proper ligand field was found to be the most efficient strategy toward higher spin reversal barriers in the design of SMMs based on single lanthanide ions.[8]
High magnetic anisotropy is necessary for achieving high energy barriers for spin reversal, but not sufficient to get an excellent SMM because the spin−lattice relaxation processes or the quantum tunneling of magnetization (QTM) may significantly affect the blocking temperature.[9−12] In particular, Raman relaxation was recently found to be the limiting process below the blocking temperature of the record-breaking Single Ion Magnets (SIM).[3,4,13]
Summary
Single molecule magnets (SMMs) enjoy renewed interest in the field of molecular magnetism[1,2] due to a rapid increase of the magnetization blocking temperatures approaching the boiling point of nitrogen[3−5] and their implementation as molecular qubits. In order to conduct detailed pulse EPR experiments and to study the spin dynamics of the complex cation [Gd(phendo)4]3+, solid state dilution samples of 1 in the isostructural [Y(phendo)4](NO3)3·xMeOH (2) were prepared with the intended GdIII molar fractions of 5%, 1%, and 0.3% (synthesis and characterization are described in the SI).
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