Magnetic field induced delocalization in hybrid electron-nuclear spin ensembles #Hyperpolarization

Published: October 8, 2021

Pagliero, Daniela, Pablo R. Zangara, Jacob Henshaw, Ashok Ajoy, Rodolfo H. Acosta, Neil Manson, Jeffrey A. Reimer, Alexander Pines, and Carlos A. Meriles. “Magnetic Field Induced Delocalization in Hybrid Electron-Nuclear Spin Ensembles.” Physical Review B 103, no. 6 (February 26, 2021): 064310.

https://doi.org/10.1103/PhysRevB.103.064310.

We use field-cycling-assisted dynamic nuclear polarization and continuous radio-frequency (RF) driving over a broad spectral range to demonstrate magnetic-field-dependent activation of nuclear spin transport from strongly hyperfine-coupled 13C sites in diamond. We interpret our observations with the help of a theoretical framework where nuclear spin interactions are mediated by electron spins. In particular, we build on the results from a four-spin toy model to show how otherwise localized nuclear spins must thermalize as they are brought in contact with a larger ancilla spin network. Further, by probing the system response to a variable driving field amplitude, we witness stark changes in the RF-absorption spectrum, which we interpret as partly due to contributions from heterogeneous multispin sets, whose zero-quantum transitions become RF active thanks to the hybrid electronnuclear nature of the system. These findings could prove relevant in applications to dynamic nuclear polarization, spin-based quantum information processing, and nanoscale sensing.