Imprinting the domain structure of a metallic antiferromagnet on thin ferromagnetic layers

Abstract

The theoretical prediction of Néel order manipulation in antiferromagnetic (AFM) Mn2Au by current induced bulk spin-orbit torques [1] and subsequent experimental realization of the same [2, 3] have led to a surge of interest in the study of this material for spintronics applications. However, the absence of a net magnetic moment in antiferromagnets poses a major challenge to the visualization of antiferromagnetic domains and it is usually resolved by complex synchrotron-based microscopy methods such as X-ray magnetic linear dichroism - photoemission electron microscopy (XMLD-PEEM) [4, 5]. In this work we present an alternative technique to image antiferromagnetic domains in-house by imprinting them on thin ferromagnetic overlayers via interfacial exchange coupling. The domains of the Mn2Au/ferromagnet bi-layer system were first observed using X-ray magnetic linear/circular dichroism – photoelectron emission microscopy for the antiferromagnetic and ferromagnetic layers, respectively. The ferromagnet was found to mimic the underlying Mn2Au domain pattern, thereby enabling us to indirectly image the AFM domains of Mn2Au using an in-house scanning electron microscope with polarization analysis (SEMPA) (Figure 1). Furthermore, superconducting quantum interference device (SQUID) magnetometry measurements were carried out to quantify the pinning field acting upon the ferromagnet and an unusually large exchange coupling was revealed at the Mn2Au/ferromagnet interface. Our results unlock novel possibilities for in-house study of antiferromagnets and take us a step further towards the realization of next generation spintronics devices based on this remarkable material.This project is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) TRR 173 268565370 (projects A01 & A05). **