UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2009 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
OPTIMIZATION OF THERMIONIC VACUUM ARC PLASMA USED FOR MULTILAYER GMR/TMR FILMS PREPARATION


Authors:
Ionut JEPU1, Ion MUSTATA1, Cristian P. LUNGU1, Victor KUNCSER2, Florin MICULESCU3, Tiberiu TUDOR4


Affiliation:
1National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania

2National Institute of Materials Physics Bucharest-Magurele, Romania

3BIOMAT Department, ”Politehnica” University, Bucharest, Romania

4Physics Department, University of Bucharest, Magurele 077125, Romania


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Keywords:


Abstract:
Optical and electrical behavior of Giant Magnetoresistive (GMR)/Tunneling Magnetoresistive (TMR) multilayer thin films were controlled adjusting thermionic vacuum arc plasma parameters. Smooth, dense and adherent films were prepared using optimized plasma conditions. A new setup for simultaneous depositions of pure materials was made, having inside the vacuum chamber three simultaneous discharges. To obtain the discharge both tungsten filaments of the thermionic vacuum arc guns were heated by a 45-55 A current. An optimization of the geometrical parameters as the distance between the cathode and the anode, the external parameters as the discharge voltage and the heating current of tungsten current filaments was performed. Structural and morphological properties of the prepared films were analyzed by scanning electron microscopy (SEM). The film’s adherence to the substrate was measured using an in-house pulling test apparatus. The behavior of the obtained films was first analyzed in a Magneto-Optical Kerr Effect (MOKE) experiment. The analysis of the films was further made by attaching four contacts on the probes using a silver conductive paste. Two of the electrodes were designed to apply a constant current on the probe, and the other two were for reading the voltage drop on the probe. The electrical resistance behavior of the prepared films was determined in a magnetic field which values varied from 0.4 T to -0.4 T. The important changes in the values of the electrical resistance of the films were observed and correlated to the plasma conditions.