In the past few years, a considerable effort has been devoted in order to grow magnetoelectric nanostructured materials. Besides fundamental science, they are very attractive in the electronic/spintronic industry as well as magnetic storage media, solar energy conversion due to their nanometer scale. It is believed that CuO is a magnetoelectric multiferroic system where a ferroelectric order is induced by the onset of a magnetic coupling at low temperatures. Furthermore, its simplest composition is the bases of cuprates which bring about the well-known high-temperature superconductivity. Bulk samples of CuO (which has an unpaired electron in the d-shell) show two antiferromagnetic phase transitions – a commensurate collinear state with the magnetic moments along the monoclinic b axis at TN ~ 213 K and an incommensurate spiral state with half of the magnetic moments in the ac plane at TN ~ 230 K
