Dynamic-nuclear-polarization-weighted spectroscopy of multi-spin electronic-nuclear clusters

TL;DR

This paper introduces a novel spectroscopy method combining field-cycling, optical spin pumping, and RF excitation to analyze complex multi-spin clusters in diamond, revealing their intricate nuclear polarization patterns and dynamics.

Contribution

It presents a new multi-dimensional spectroscopy technique for probing hybrid electronic-nuclear spin clusters in solids, enhancing understanding of their spin dynamics.

Findings

Revealed complex nuclear polarization patterns in spin clusters.

Demonstrated the impact of hyperfine-coupled nuclei on spin dynamics.

Developed a method to reconstruct multi-dimensional spectra of spin states.

Abstract

Nuclear spins and paramagnetic centers in a solid randomly group to form clusters featuring nearly-degenerate, hybrid states whose dynamics are central to processes involving nuclear spin-lattice relaxation and diffusion. Their characterization, however, has proven notoriously difficult mostly due to their relative isolation and comparatively low concentration. Here, we combine field-cycling experiments, optical spin pumping, and variable radio-frequency (RF) excitation to probe transitions between hybrid multi-spin states formed by strongly coupled electronic and nuclear spins in diamond. Leveraging bulk nuclei as a collective time-integrating sensor, we probe the response of these spin clusters as we simultaneously vary the applied magnetic field and RF excitation to reconstruct multi-dimensional spectra. We uncover complex nuclear polarization patterns of alternating sign that we qualitatively capture through analytical and numerical modeling. Our results unambiguously expose the impact that strongly-hyperfine-coupled nuclei can have on the spin dynamics of the crystal, and inform future routes to spin cluster control and detection.