# Toward Two-Dimensional van der Waals Magnon Transport Devices: WTe2 Electrodes for Efficient Magnon Spin Injection and Detection

## TL;DR

Researchers found that WTe2 can efficiently inject and detect magnon spins in two-dimensional devices, outperforming traditional materials like platinum.

## Contribution

The study introduces WTe2 as a novel two-dimensional material for efficient magnon spin injection and detection without requiring a magnetic field.

## Key findings

- WTe2 enables efficient injection and detection of in-plane and out-of-plane magnon spins.
- WTe2's charge-to-spin conversion efficiency is 0.45 and 1.7 times higher than platinum for in- and out-of-plane spin injection.
- Hybrid devices using WTe2 and CrPS4 demonstrate unconventional spin conversion mechanisms.

## Abstract

One of the bottlenecks
toward all two-dimensional material-based
magnon transport devices is the absence of a two-dimensional material
for the efficient injection and detection of magnon spins. Here, we
demonstrate that WTe2, a layered, nonmagnetic van der Waals
material, functions as an efficient spin injector and detector for
magnon spins. It enables injection and detection of spins polarized
in-plane via the conventional spin Hall effect and magnon spins polarized
out-of-plane through unconventional charge-to-spin interconversion
mechanisms. Such dual functionality is not achievable with conventional
electrodes such as platinum or permalloy in the absence of a magnetic
field. Using CrPS4, an insulating two-dimensional antiferromagnet,
we employ a hybrid nonlocal device geometry where magnon spins are
injected and detected via conventional platinum and WTe2 contacts. We find that the effective charge-to-spin conversion efficiency
of WTe2 is about 0.45 and 1.7 times for the injection of
in- and out-of-plane polarized spins, respectively, compared to the
in-plane polarized spin injection efficiency of platinum electrodes.