Archive ouverte HAL – Exactly solvable model for dynamic nuclear polarization

Inés Rodríguez-Arias 1 Markus Müller 2, 3 Alberto Rosso 1 Andrea De Luca 4

Physical Review B : Condensed matter and materials physics, American Physical Society, 2018, 98 (22), 〈10.1103/PhysRevB.98.224202〉

We introduce a solvable model of driven fermions that elucidates the role of the localization transition in driven disordered magnets, as used in the context of dynamic nuclear polarization. Instead of spins, we study a set of non-interacting fermions that are coupled locally to nuclear spins and tend to hyperpolarize them. The induced hyperpolarization is a fingerprint of the driven steady state of the fermions, which undergo an Anderson Localization (AL) transition upon increasing the disorder. Our central result is that the maximal hyperpolarization level is always found close to the localization transition. In the limit of small nuclear moments the maximum is pinned to the transition, and the hyperpolarization is strongly enhanced by multi-fractal correlations in the critical state of the nearly localized driven system, its magnitude reflecting multi-fractal scaling.

  • 1. LPTMS - Laboratoire de Physique Théorique et Modèles Statistiques
  • 2. PSI - Paul Scherrer Institute
  • 3. ICTP - Abdus Salam International Centre for Theoretical Physics [Trieste]
  • 4. Rudolf Peierls Center for Theoretical Physics