# Nonlocal magnon spin transport in NiFe$_2$O$_4$ thin films

## TL;DR

This study demonstrates room-temperature nonlocal magnon spin transport in NiFe$_2$O$_4$/Pt bilayers, revealing a magnon relaxation length of about 3.1 micrometers and highlighting the relationship between magnon signals and magnetization behavior.

## Contribution

It provides the first detailed measurement of nonlocal magnon spin transport in NiFe$_2$O$_4$ thin films at room temperature, including the estimation of magnon relaxation length.

## Key findings

- Magnon spin signals depend on magnetic field and magnetization.
- Magnon relaxation length estimated at 3.1 micrometers.
- Local magnetoresistance does not correlate with NFO magnetization.

## Abstract

We report magnon spin transport in nickel ferrite (NiFe$_2$O$_4$, NFO)/ platinum (Pt) bilayer systems at room temperature. A nonlocal geometry is employed, where the magnons are excited by the spin Hall effect or by the Joule heating induced spin Seebeck effect at the Pt injector, and detected at a certain distance away by the inverse spin Hall effect at the Pt detector. The dependence of the nonlocal magnon spin signals as a function of the magnetic field is closely related to the NFO magnetization behavior. In contrast, we observe that the magnetoresistance measured locally at the Pt injector does not show a clear relation with the average NFO magnetization. We estimate the magnon spin relaxation length to be 3.1 $\pm$ 0.2 $\mu$m in the investigated NFO samples.