Modular Approach to Spintronics [spintronics]

Module: Pure Spin Condutor - Magnon Transport in Ferromagnetic Insulator

This page is under development

This model enables simulation of a novel phenomenon of pure spin conduction by magnon diffusion in ferromagnetic insulators such as yttrium-iron-garnet (YIG). Such materials do not allow charge to flow but nevertheless allow spins to flow that are longitudinal to the magnetization direction. The pure spin conduction is characterized by magnon relaxation length, magnon conductivity and interface spin conductance. Note that magnon conductivity in such material is different from charge conductivity which is very low since they are insulators. These materials can be used in spin-based device designs to avoid current shunting effect.

Model Description

The model [1] consists of two modules: (a) bulk and (b) FMI|NM interface modules. The bulk module, which is a π - model, takes into account the pure spin (longitudinal to the magnetization direction) transport by magnon diffusion. The series conductance takes into account the spin transmission from one surface to the other, while the shunt conductances take into account the spin relaxation. The series conductance has the interface conductance for the spins that are longitudinal to the magnetization direction. The shunt conductance captures the spin relaxation for transverse spins at the interface. The interface module is similar to already existing FM|NM module except the charge conductance is negligible compared to the spin conductance since FMI is an insulator. The models are shown below:

with the following conductances matrices in c-z-x-y basis where c is charge and z, x, y are spin polarization.

Parameters

Parameter	Symbol	Unit
Pure Spin Resistivity
Magnon Diffusion Length
Length
Cross-Sectional Area
Interface Spin Conductance (Longitudinal Spins)
Real Part of Spin Mixing Conductance (Transverse Spins)
Imaginary Part of Spin Mixing Conductance (Transverse Spins)

Download

The module, as a part of the library, can be downloaded here.

Contact Information

Please contact Shehrin Sayed ( ssayed AT berkeley DOT edu or ssayed AT lbl DOT gov) for questions or comments regarding this page.

References

[1] S. Sayed, V. Q. Diep, K. Y. Camsari, and S. Datta, "Spin Funneling for Enhanced Spin Injection into Ferromagnets". Scientific Reports, 6: 28868 (2016). (Link).