Exploring the Organometallic Route to Molecular Spin Qubits: The [CpTi(cot)] Case

Abstract

The coherence time of the 17‐electron, mixed sandwich complex [CpTi(cot)], (η8‐cyclooctatetraene)(η5‐cyclopentadienyl)titanium, reaches 34 μs at 4.5 K in a frozen deuterated toluene solution. This is a remarkable coherence time for a highly protonated molecule. The intramolecular distances between the Ti and H atoms provide a good compromise between instantaneous and spin diffusion sources of decoherence. Ab initio calculations at the molecular and crystal packing levels reveal that the characteristic low‐energy ring rotations of the sandwich framework do not yield a too detrimental spin‐lattice relaxation because of their small spin–phonon coupling. The volatility of [CpTi(cot)] and the accessibility of the semi‐occupied, non‐bonding dnormalz2 orbital make this neutral compound an ideal candidate for single‐qubit addressing on surface and quantum sensing in combination with scanning probe microscopy.

Understanding the magnetic anisotropy for linear sandwich [Er(COT)]+-based compounds: a theoretical investigation

“…5,6 The interest in the magnetic properties of sandwich organometallic compounds has considerably grown in the last few years, also for applications as molecular spin qubits. 7–9 Layfield et al reported a dysprosium metallocene cation [(Cp iPr5 )Dy(Cp*)] + showing an exceptionally high anisotropy barrier U eff of 1541 cm −1 , and its 100 s blocking temperature T B is 65 K. 10 In 2022, Long, et al just reported one dilanthanide complex with metal–metal bonding whose energy barrier and blocking temperature are up to 1631 cm −1 and 72 K, respectively. 11 Recently, we also theoretically predicted that the energy barrier and blocking temperature of one two-coordinate [Co(C(SiMe 2 ONaphthyl) 3 ) 2 ] 12 can be enhanced up to 1559.1 cm −1 and 90 K, respectively, through the structural distortion.…”

Assessing the Nature of Chiral-Induced Spin Selectivity by Magnetic Resonance

“…44−58 In addition, the capability to link these qubits to other units make them ideal candidates for the proposed architecture. As a model example, we consider a qubit = g e ∓ Δg/ 2, with Δg = 0.002, g Q = (1.98, 1.98, 1.96), as typical for VO 2+ or Ti 3+ , 42 T 1 = 2 μs, T 2 = 0.5 μs, and T R = 10 μs. Inhomogeneous broadening of the parameters is included by a Gaussian broadening of the peaks with fwhm 2.35 mT.…”

A Molecular Approach to Quantum Sensing

“…To address these challenges, we and others are employing coordination chemistry to rationally control both the physical and electronic structure as well as coherence properties including quantum state lifetimes ( T 1 ) and coherence times ( T m ). ,,− Ligand design provides an immediate route to achieve long T 1 and T m or optical initialization and read-out pathways. Further tuning parameters such as spin–orbit coupling, crystal field splitting, and electron–nuclear hyperfine interaction provide additional handles to optimize the requisite sensor criteria mentioned above. ,,, In addition, harnessing parameters such as spin–orbit coupling and hyperfine interactions can elicit detection of physical parameters beyond magnetic fields, including electric fields and pressure. ,, Lastly, employing anisotropic electronic structures of transition metals can provide orientation information during sensing, enhancing the spatial resolution of the molecular sensor. , …”