Combinatorial Fe–Co thin film magnetic structures obtained by thermionic vacuum arc method

Magnetoresistive Fe–Co based thin film structures were produced using thermionic vacuum arc method. The purpose of this work was to obtain significant magnetic response on different granular combinatorial structures. The Giant Magnetoresistive (GMR) and combination between GMR and Tunneling Magnetoresistive (TMR) properties of the thin film structures were the aim of the work. The proposed method in order to obtain the desired granular structures is based on electron beam emitted by an externally heated cathode, accelerated by a high anodic potential. rk consisted in preparing two sets of samples, first being a combination between Fe–Co as magnetic materials embedded in a Cu matrix, with a total thickness of 200 nm. The second structure was a combination between Fe–Co (50%–50%) alloy, embedded in a matrix of Cu combined with MgO with a thickness of 200 nm. Both sets of samples were obtained by three simultaneous types of discharges. Because of the substrate positioning in respect with the three anode–cathode systems, different material concentrations were obtained, confirmed by Energy Dispersive Spectroscopy (EDS) measurement results. Structural and morphological properties were investigated using Scanning Electron Microscopy; Atomic Force Microscopy and EDS. Electrical properties of the obtained samples were studied using the 4 point measurement method. The magnetic properties were first studied using a non-destructive optical method called MOKE (Magneto-Optical Kerr Effect). Electrical resistance behavior of the granular type structures was studied for different values of the magnetic field, up to 0.3 T, at different values of the sample temperature. The magnetoresistive effect obtained for the two sets of samples varied from 1.5% to 81% in respect with the substrate positioning and sample temperature for a constant magnetic field.