# Spin decoherence independent of antiferromagnetic order in IrMn

## TL;DR

This study shows that the decoherence of spin currents in IrMn is unaffected by its antiferromagnetic order, challenging assumptions about magnetic order's role in spin decoherence.

## Contribution

It provides experimental evidence that spin decoherence in IrMn is independent of its antiferromagnetic order, which is a novel insight in spintronics.

## Key findings

- Spin decoherence is isotropic with respect to antiferromagnetic order orientation.
- Pinned antiferromagnetic order does not influence spin decoherence.
- Resonance linewidth increases are unrelated to spin decoherence mechanisms.

## Abstract

We investigate the impact of pinned antiferromagnetic order on the decoherence of spin current in polycrystalline IrMn. In NiFe/Cu/IrMn/CoFe multilayers, we coherently pump an electronic spin current from NiFe into IrMn, whose antiferromagnetic order is globally pinned by static exchange-bias coupling with CoFe. We observe no anisotropic spin decoherence with respect to the orientation of the pinned antiferromagnetic order. We also observe no difference in spin decoherence for samples with and without pinned antiferromagnetic order. Moreover, although there is a pronounced resonance linewidth increase in NiFe that coincides with the switching of IrMn/CoFe, we show that this is not indicative of anisotropic spin decoherence in IrMn. Our results demonstrate that the decoherence of electron-mediated spin current is remarkably insensitive to the magnetization state of the antiferromagnetic IrMn spin sink.