Antiferromagnetism, which manifests as the antiparallel alignment of neighboring magnetic moments, is one of the most important magnetic orderings. Although sharing nearly the same mechanism with ferromagnetism, antiferromagnetism was discovered much later due to the compensated magnetic structure which is of very weak response to magnetic field. Because of the same reason, the characterization of the ordering temperature and magnetic structure of antiferromagnetic material is much more difficult than that of the ferromagnet, which usually requires higher sensitivity in magnetometry and larger sample volume. When the antiferromagnetic material is made into a geometry with confinement such as ultra-thin film, these measurements are especially challenging. In spite of these difficulties, the research interests of antiferromagetism in thin films have been growing in the last several decades with the motivations not only from commercial applications like exchange bias, but also form the emergence of novel phenomena in confined antiferromagnetic systems such as the recent discovered high-Tc superconductivity in FeSe films.