Nuclear spin pumping and electron spin susceptibilities

TL;DR

This paper introduces a novel formalism for analyzing nuclear spin dynamics influenced by hyperfine interactions with non-equilibrium electron spins, avoiding traditional limitations by not relying on energy scale separation.

Contribution

It provides a new approach to evaluate nuclear spin dynamics that is more general and practical than traditional rate equation methods.

Findings

Formalism accurately describes nuclear spin dynamics

Method applicable without energy scale separation

Overcomes limitations of traditional approaches

Abstract

In this work we present a new formalism to evaluate the nuclear spin dynamics driven by hyperfine interaction with non-equilibrium electron spins. To describe the dynamics up to second order in the hyperfine coupling, it suffices to evaluate the susceptibility and fluctuations of the electron spin. Our approach does not rely on a separation of electronic energy scales or the specific choice of electronic basis states, thereby overcoming practical problems which may arise in certain limits when using a more traditional formalism based on rate equations.