Relevance of Dzyaloshinskii–Moriya spectral broadenings in promoting spin decoherence: acomparative pulsed-EPR study of two structurallyrelated iron(III) and chromium(III) spin-triangle molecular qubits.
Robert J, Parizel N, Turek P and Boudalis A K.
Physical Chemistry Chemical Physics, 2019.
Spectral broadenings due to Dzyaloshinskii–Moriya interactions (DMI) were assessed with respect to thedecoherence they induce through increased spin–spin interactions, as the role of DMI in developingmagnetoelectric spin-chirality qubits is gaining recognition. The structurally related spin triangles[Fe3O(PhCOO)6(py)3]ClO4py (Fe3) and [Cr3O(PhCOO)6(py)3]ClO40.5py (Cr3) were studied as frozen py-d5solutions with various pulsed Electron Paramagnetic Resonance (EPR) spectroscopy experiments, andunder identical experimental conditions. Field-swept Hahn echo experiments revealed a match withcontinuous-wave (CW) spectra, while variable-temperature saturation/inversion recovery and Hahn echodecay experiments were used to extract the thermal evolutions of the spin–lattice relaxation and phase-memory times (T1andTm, respectively). Nutation experiments revealed Rabi oscillations demonstratingthat the spins of the complexes could be coherently manipulated. Careful comparisons ofTmtimesconfirmed hyperfine interactions with the magnetic nuclei of the metal ions as an intrinsic source ofdecoherence. Comparisons of Rabi damping times revealed that DMI-induced spectral broadenings play adiscernible but moderate role as an extrinsic source of decoherence for the nutation experiments and thatthey are not particularly detrimental to spin manipulations