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Jason S. R. McCoombs

Publications and source records attributed to Jason S. R. McCoombs.

2 recordsLinked to original sources

Coupling between molecular exchange qubits

Spin triangles are promising systems for defining and manipulating scalar degrees of freedom, such as chirality, partial spin sums, or combinations between the two. Here we extend this analysis to dimers formed by pairs of spin triangles, coupled by exchange or dipolar interactions. We show that the weak-coupling limit warrants the introduction of an effective two-qubit picture, and derive the expressions of the related Hamiltonians as a function of the underlying physical interaction between the triangles. We benchmark this two-qubit Hamiltonian against the microscopic one, and discuss the observable effects of the inter-triangle coupling on the spin-electric transitions between states with different chiralities or partial-spin sums.

quant-ph↗

Second-harmonic signal in electric-field-modulated EPR spectra of Fe3 spin triangles

We present electric-field-modulated electron paramagnetic resonance (EFM-EPR) measurements on centrosymmetric single crystals of the molecular spin triangle $\mathrm{[{Fe_3}O({O_2}CPh){_6}(py){_3}]ClO{_4}{\cdot}py}$ ($\bf{Fe_3}$). We provide the first observation of second harmonic EFM-EPR signal in polynuclear magnetic molecules. This signal is simulated and explained in terms of an electric-field induced modulation of the isotropic exchange in the molecule, and of their symmetry lowering resulting from a Jahn-Teller effect. Additionally, an unexpected first harmonic EFM-EPR signal is observed. Various plausible symmetry-breaking mechanisms are discussed in an attempt to explain this feature, whose observation is unexpected in a nominally centrosymmetric crystal.

cond-mat.mtrl-sci↗