Experimental and Theoretical Study of the Ultrafast Dynamics of a Ni₂Dy₂‐Compound in DMF After UV/Vis Photoexcitation

Abstract

We present a combined experimental and theoretical study of the ultrafast transient absorption spectroscopy results of a {Ni2Dy2}‐compound in DMF, which can be considered as a prototypic molecule for single molecule magnets. We apply state‐of‐the‐art ab initio quantum chemistry to quantitatively describe the optical properties of an inorganic complex system comprising ten atoms to form the chromophoric unit, which is further stabilized by surrounding ligands. Two different basis sets are used for the calculations to specifically identify two dominant peaks in the ground state. Furthermore, we theoretically propagate the compound's correlated many‐body wavefunction under the influence of a laser pulse as well as relaxation processes and compare against the time‐resolved absorption spectra. The experimental data can be described with a time constant of several hundreds of femtoseconds attributed to vibrational relaxation and trapping into states localized within the band gap. A second time constant is ascribed to the excited state while trap states show lifetimes on a longer timescale. The theoretical propagation is performed with the density‐matrix formalism and the Lindblad superoperator, which couples the system to a thermal bath, allowing us to extract relaxation times from first principles.

Laser-Controlled Implementation of Controlled-NOT, Hadamard, SWAP, and Pauli Gates as Well as Generation of Bell States in a 3d–4f Molecular Magnet

“…The main vibrational eigenmodes of our molecule have energies between 500 and 2000 cm –1 , corresponding to periods of a few hundred femtoseconds. , Electronic-energy calculations including vibronic geometry deformations lead to energy shifts of up to 4 meV, which lie well within the detuning tolerance of our processes (the fidelities remain above 85% for detunings of up to 20 meV). The transition-matrix elements also do not significantly change.…”

“…This molecular magnet contains two dysprosium and two nickel atoms, as well as oxygen atoms bonded covalently and acting as bridges between these metal atoms, altogether constituting the central metal core of the cluster. , We profit from the synergy effect of the strong spin–orbit coupling of the Dy 4f orbitals and the large spatial anisotropy of the Ni 3d orbitals. Much understanding of the laser-induced spin dynamics has already been achieved in this system; that is, the relaxation times have been experimentally and theoretically extracted and explained, the intermediate states of this dynamics (some of which are trapping states and thus responsible for the slowest relaxation times) have been identified, and the most prominent partial metal-to-oxygen charge-transfer excitations contributing to the pertinent correlated many-body states have been discerned . In the remainder of the Letter [Dy 2 Ni 2 (L) 4 (NO 3 ) 2 (DMF) 2 ] and [Dy 2 Ni 2 O 6 ] are referred to as the real molecular magnet and the core system , respectively.…”

Investigation of the exact spin channels in laser-induced spin dynamics in two mononuclear Cu(ii) complexes

“…The electronic ground-state absorption spectra for the complexes serve well as the yard stick to measure the accuracy of the theoretical calculations of the molecular magnets in our previous works 41,63 when compared to experimental spectra. Magnetic measurements for both compounds were performed on a MPMS XL-5 SQUID (superconductivity) on finely ground polycrystalline samples.…”

Using single and double laser pulses on the molecular Ni4@C48H36 system to design integrated nanospintronic units

“…37 For instance, previously we suggested the essential “ERASE” logic functionality and spin transfer in the quasilinear [Fe–O–CO] + molecular ion, a topological spin-charge gearbox on the real molecular magnet Co 3 Ni(EtOH) + , and a two-qubit system in [Dy 2 Ni 2 (L) 4 (NO 3 ) 2 (DMF) 2 ]. 38–41 In general, small magnetic molecules with multiple magnetic centers allow for both spatial and spectroscopic spin manipulation. 42,43…”