Studies of the magnetic structure at the ferromagnet-antiferromagnet interface

Antiferromagnetic layers are a scientifically challenging component in magn etoelectronic devices, such as magnetic sensors in hard-disk heads, or magn etic random-access memory (RAM) elements. In this paper, it is shown that p hotoelectron emission microscopy (PEEM) is capable of determining the magne tic structure at the interface of ferromagnets and antiferromagnets with hi gh spatial resolution (down to 20 nm). Dichroism effects at the L edges of the magnetic 3d transition metals, using circularly or linearly polarized s oft X-rays from a synchrotron source, give rise to a magnetic image contras t. Images, acquired with the PEEM2 experiment at the Advanced Light Source, show magnetic contrast for antiferromagnetic LaFeO3, microscopically resol ving the magnetic domain structure in an antiferromagnetically ordered thin film for the first time. Magnetic coupling between LaFeO3 and an adjacent Co layer results in a complete correlation of their magnetic domain structu res. From field-dependent measurements, a unidirectional anisotropy resulti ng in a local exchange bias of up to 30 Oe in single domains could be deduc ed. The elemental specificity and the quantitative magnetic sensitivity ren der PEEM a perfect tool to study magnetic coupling effects in multilayered thin-film samples.