Orthogonal interlayer coupling in an all-antiferromagnetic junction

Abstract

The interlayer coupling of two ferromagnetic layers results in found of giant magnetoresistance, which forms the foundation of spintronics and accelerates the development of information technology. Compared with ferromagnets, antiferromagnets (AFMs) possess huge potential in ultrafast and high-density data processing and information storage because of their terahertz spin dynamics and subtle stray field. The interlayer coupling in AFMs has long been neglected, because the collinear parallel and antiparallel arrangements of AFMs are indistinguishable. However, the noncollinear interlayer coupling in AFMs is detectable, and can be a potential candidate for practical antiferromagnetic spintronic devices. Here we demonstrate orthogonal interlayer coupling at room temperature in an all-antiferromagnetic junction Fe2O3/Cr2O3/Fe2O3, where the Néel vectors in the top and bottom functional materials Fe2O3 are strongly orthogonally coupled and the coupling strength of which is significantly affected by the thickness of the antiferromagnetic Cr2O3 spacer. From the energy and symmetry analysis, the direct coupling via uniform magnetic ordering is excluded. The coupling is proposed to be mediated by quasi-long range order in the spacer. Besides the fundamental significance, the strong coupling in an antiferromagnetic junction makes it a promising building block for practical antiferromagnetic spintronics with high-speed operation and ultrahigh-density integration.