Separative magnetization transport: theory, model, and experiment

Abstract

We present a theoretical framework for modeling the transport of any number of globally con- served quantities, in any spatial configuration, and apply it to obtain a model of magnetization transport for spin-systems with two spin-species. The framework allows an entropy function to define a model that explicitly respects the laws of thermodynamics. A one-species model is derived as a special case. In the high spin-temperature (linear) limit, this model is shown to be equivalent to the model of nuclear spin transport of Genack and Redfield. The two-species model is novel in that it describes systems of two spin-species and systems with large polarization. It is explored numerically and shown to be consistent with experimental results, which are also presented, but are insufficient to validate the model. This is followed by a numerical exploration of a potential experiment that could validate the model. Analytic, steady state solutions for the one- and two-species models are derived. The separative quality of transport is quantified by two figures of merit: one static and the other dynamic. The theoretical framework, two-species model, and experimental results provide a foundation for further study of separative magnetization transport (SMT), and in particular the study of harnessing it to induce hyperpolarization by optimizing the presented figures of merit.