Ferromagnetism in Ni doped ZnS thin films: Effects of Ni concentration and swift heavy ion irradiation

• Ferromagnetism is achieved via Ni doping in ZnS thin films.
• The magnetic properties have been studied as function Ni concentration and swift heavy ion irradiation.
• The increase in Ni concentration and swift heavy ion irradiation cause the decrease in magnetization of films.
• The decrease of magnetization is ascribed to the formation of ion track (or columnar defects).

The magnetic properties of Ni doped ZnS thin films fabricated at substrate temperature of 400 °C by means of pulsed laser deposition are presented. The films show crystalline wurtzite structure. Optical absorption and transmission electron microscopic studies indicate that Ni has been appropriately substituted on Zn tetrahedral site. The films show ferromagnetism up to room temperature. The magnetization in the films decreases with increase of Ni concentration. Swift heavy ion (SHI) irradiations have been carried out using 120 MeV Ag ions for the modification of structural and magnetic properties of the films. SHI irradiation suggests the formation columnar ion track inside the films causing decrease in magnetization.