First Demonstration of Magnetoelectric Coupling in a Polynuclear Molecular Nanomagnet: Single‐Crystal EPR Studies of [Fe₃O(O₂CPh)₆(py)₃]ClO₄⋅py under Static Electric Fields

Abstract

Single-crystal EPR experiments show that the highly symmetric antiferromagnetic half-integer spin triangle [Fe O(O CPh) (py) ]ClO ⋅py (1, py=pyridine) possesses a S =1/2 ground state exhibiting high g-anisotropy due to antisymmetric exchange (Dzyaloshinskii-Moriya) interactions. EPR experiments under static electric fields parallel to the triangle's plane (i.e., perpendicular to the magnetic z-axis) reveal that this ground state couples to externally applied electric fields. This magnetoelectric coupling causes an increase in the intensity of the intradoublet EPR transition and does not affect its resonance position when B ∥z. The results are discussed on the basis of theoretical models correlating the spin chirality of the ground state with the magnetoelectric effect.

Electric Field Control of Spins in Molecular Magnets

“…We note that a study of the E-field effect on the continuous-wave ESR spectrum of a crystal of a polynuclear molecular nanomagnet was reported after the submission of this article [37].…”

Determination of the Distributions of the Spin-Hamiltonian Parameters in Spin Triangles: A Combined Magnetic Susceptometry and Electron Paramagnetic Resonance Spectroscopic Study of the Highly Symmetric [Cr3O(PhCOO)6(py)3](ClO4)·0.5py

“…It was then proposed that instead of this scheme, the same molecules could be used as spin qubits, by using employing their spin chirality as the computational degree of freedom, which would allow electric manipulation 14,15 and longer coherence times, 16 a proposition recently validated by us through the observation of magnetoelectric coupling in complex [Fe 3 O(PhCOO) 6 (py) 3 ](ClO 4 )·py. 17 As pointed out by Di Vincenzo in his famous checklist, 18 in order to employ a system for a qubit implementation, we need a precise description of its spin Hamiltonian. Indeed, the gross picture for spin triangles has been relatively well elucidated for some time now: 19 for an equilateral magnetic system in which only isotropic exchange interactions occur, according to multispin Hamiltonian, with a magnetic asymmetry ΔJ = J -J'; 20 this form implies that whereas the isotropic exchange couplings J and J' have the same sign, they are of different sizes.…”

Relevance of Dzyaloshinskii–Moriya spectral broadenings in promoting spin decoherence: a comparative pulsed-EPR study of two structurally related iron(iii) and chromium(iii) spin-triangle molecular qubits

“…(ii) A higher-field derivative-like feature which corresponds to z⊥B 0 (g ⊥ ) and whose value also depends on parameters ΔJ = J -J' and |G|. The CW spectra of both complexes in frozen pyridine-d 5 solutions were qualitatively similar to the solid-state ones, 28,37 albeit presenting differences in the shape and width of their non-parallel part. The CW spectrum of Fe 3 revealed resonances over a broad magnetic field range (3500-4500 G; g ~ 2.00-1.65), indicative of significant magnetic anisotropy, which is in line with the strong DMI (G z ~ 1.7-2.0 cm -1 ) determined by solid-state studies.…”

“…Moreover, due to their non-centrosymmetric structures, their spins were postulated to couple with external electric fields, thus allowing their direct electric manipulation, including their long-range coupling by microwave electric fields inside resonant cavities; 27 indeed this hypothesis has recently been confirmed for [Fe 3 O(PhCOO) 6 (py) 3 ]ClO 4 ⋅py (Fe 3 ) by us 28 and for a Cu II 3 triangle by Liu et al…”

“…A "brute-force" strategy consists in the creation of magnetically quiet environments through isotope engineering. The state of the art in this approach is the use of fragments from the "Avogadro crystal", a 5 kg isotopically ultrapure 28 Si single crystal, initially prepared for the redefinition of Avogadro's number; 16 31 P donor atom implants in such a piece exhibited coherence times as long as 3 hours. 17 The molecular analogue of this strategy is the design of MNMs whose environments (ligands, solvents, counterions) either consist of elements which are naturally poor in magnetic isotopes (C, S), or are isotopically engineered to contain nuclei with small nuclear magnetic moments (e.g.…”