Textured Nd-Fe-B hard magnetic thin films prepared by pulsed laser deposition with single alloy targets

Nd-Fe-B thin films have been successfully developed by Pulsed Laser Deposition (PLD) onto silicon substrates. In order to explore the crucial role of target composition during PLD, five single alloy targets, representing specific atomic compositions (Nd/Fe atomic ratio varied in the range 0.18–0.47) have been tested and studied. In a determined deposition temperature range of 550 °C-630 °C, thin films made from a target with Nd/Fe = 0.45 present the best hard magnetic properties, a quasi-single magnetic phase, both coercivity and remanence above 1 T and a square loop shape. FIB-ESB analyses associated with XRD, SEM and SQUID-VSM magnetic measurements indicate that the high values of both remanent magnetization and coercivity are ascribed to film texturation and to partial decoupling of the hard magnetic Nd₂Fe₁₄B grains by a secondary Nd-rich phase. PLD performed with other target compositions and non-optimized deposition temperatures leads to poorer magnetic properties, owing to the presence of soft magnetic phase and non-textured or oxidized thin films.