Magnetism and magnetooptics features of Zn1-xCoxOy thin films grown by pulsed laser deposition

The results of a comprehensive study of structural, magnetic and magneto-optical properties of 10-262 nm thick Zn1-xCoxOy films (x = 0-0.3) grown on c-sapphire substrates by pulsed laser deposition (PLD) method are present. It is revealed that all of the synthesized Zn1-xCoxOy films possess a wurtzite structure with the following lattice parameters: a = 3.2495 Å, c = 5.2329-5.2485 Å. It is detected that ferromagnetic properties of Zn1-xCoxOy films at room temperature vary non-monotonically with the increase of Co concentration. The strongest ferromagnetic signal is observed in the Zn0.87Co0.13Oy film due to the largest number of metallic Co clusters formed in the sample. A further increase of dopant concentrations in the films leads to the oxidation of metallic Co and the development of the paramagnetic Co3O4 phase which result in the decrease of the ferromagnetic signal. It is determined that specific magnetic characteristics of Zn1-xCoxOy samples do not depend on the film thickness. Characteristics of transversal Kerr effect pertaining to cobalt concentration in Zn1-xCoxOy films as well as thickness of the samples are studied for the first time. The correlation between the amplitude of the magneto-optical signal and the magnetization value of the films is established.