What does this research mean for the field?

Molecular spin qubits constructed from a nitronyl-nitroxide ligand and transition metal ions exhibit robust quantum coherence, with varying phase memory times depending on temperature and metal ion used. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research aims to explore the qubit behavior of heterospin complexes constructed from nitronyl-nitroxide ligands and transition metals.

March 16, 2026Open Access

Investigation of Hyperfine Interactions in Molecular Spin Qubits Constructed from A Nitronyl-Nitroxide Ligand and Transition Metal Ions

Key Points

This research aims to explore the qubit behavior of heterospin complexes constructed from nitronyl-nitroxide ligands and transition metals.
Investigated two S = 1/2 heterospin complexes using pulse EPR methods.
Compared phase memory times at different temperatures (100 K and low temperatures).
Measured spin-lattice relaxation times and hyperfine couplings using HYSCORE and ENDOR techniques.
Complex 1 shows a longer phase memory time at 100 K (0.9 μs) than complex 2 (0.12 μs).
At low temperatures, complex 2 exhibits a longer phase memory time (3.7 μs at 5.5 K) compared to complex 1 (1.78 μs at 5.2 K).
Using CPMG detection, phase memory times of up to 18 μs and 7 μs are recorded for complexes 1 and 2, respectively, at 5 K.
Complex 1 has a longer spin-lattice relaxation time than complex 2, attributed to strong spin-orbit coupling.

Abstract

The qubit behavior of two S = 1/2 heterospin complexes with the general formula (Et3NH)M(hfac)2L has been investigated by pulse EPR methods (M = Zn (1) and Ni (2), hfac- is the coligand hexafluoroacetylacetonate and L- is the deprotonated nitrophenol-substituted NIT radical 2-(2-hydroxy-3-methoxy-5-nitrophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-3-oxide-1-oxyl). Robust quantum coherence is observed in both compounds. At 100 K, 1 shows a longer phase memory time, Tm (0.9 μs) than 2 (0.12 μs), while at very low temperatures, the opposite is true (1: 1.78 μs at 5.2 K; 2: 3.7 μs at 5.5 K). With CPMG detection, longer Tm up to18 μs (1) and 7 μs (2) at 5 K is measured. The spin-lattice relaxation time (T1) is also longer for 1 than for 2, due to strong spin-orbit coupling in the latter. HYSCORE and ENDOR investigations quantified the hyperfine couplings to 19F, 1H, 67Zn, and 14N, providing clear insights into the low temperature decoherence paths in the two qubits.

Investigation of Hyperfine Interactions in Molecular Spin Qubits Constructed from A Nitronyl-Nitroxide Ligand and Transition Metal Ions

Key Points

Abstract

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