Two-electron two-nucleus effective Hamiltonian and the spin diffusion barrier.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39752498.
- Also identified by DOI 10.1126/sciadv.adr7168 and PMC identifier 11698094.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Dynamic nuclear polarization (DNP) and emerging quantum technologies rely on the spin transfer in electron-nuclear hybrid quantum systems. Spin transfers might be suppressed by larger couplings, e.g., hyperfine couplings suppressing nuclear dipolar flip-flops ("spin diffusion barrier"). We apply the Schrieffer-Wolff transformation to a two-electron two-nucleus spin system involving dipolar and hyperfine couplings in their tensorial form and study possible polarization-transfer processes. Among the different effective Hamiltonian matrix elements investigated is an energy-conserving electron-nuclear four-spin flip-flop, which combines an electronic with a nuclear dipolar flip-flop. The relevance of this electron-nuclear four-spin flip-flop for nuclear spin diffusion close to electrons is supported by model fits of HypRes-on experimental data. We connect the closely related fields of magnetic resonance and quantum information and provide a model that explains how all nuclear spins can contribute to the hyperpolarization of the bulk without a spin diffusion barrier in DNP.