Modeling spin transport with current-sensing spin detectors

TL;DR

This paper derives an analytical Green's function for current-sensing spin detectors, compares it with simulations and experiments, and highlights the importance of accurate boundary conditions in modeling spin transport.

Contribution

It provides a new analytical model for spin detector impulse response incorporating proper boundary conditions, improving accuracy over simpler approximations.

Findings

In strong drift regimes, spin current response approximates spin density times drift velocity.

In weak drift fields, neglecting boundary conditions causes large errors in transit time estimates.

The full Green's function is essential for accurate spin transport modeling in low-field conditions.

Abstract

By incorporating the proper boundary conditions, we analytically derive the impulse response (or "Green's function") of a current-sensing spin detector. We also compare this result to a Monte-Carlo simulation (which automatically takes the proper boundary condition into account) and an empirical spin transit time distribution obtained from experimental spin precession measurements. In the strong drift-dominated transport regime, this spin current impulse response can be approximated by multiplying the spin density impulse response by the average drift velocity. However, in weak drift fields, large modeling errors up to a factor of 3 in most-probable spin transit time can be incurred unless the full spin current Green's function is used.