Tunnel magnetoimpedance in cobalt discontinuous films

• Published in: Journal of magnetism and magnetic materials Vol. 205; no. 2; pp. 170 - 176
• Main Authors: Schelp, L.F, Rosa, E.L, Maurice, J.-L, Petroff, F, Vaurès, A
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1999; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Discontinuous thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in interface structures; Exact sciences and technology; Impedance spectroscopy; Metal-nonmetal contacts; Physics; Tunnel magnetoresistance; Tunneling; 73.61.−r; 36.40.Mr; 73.40.Rw; 73.50.−h; Tunnel magnetoresistance; Discontinuous thin films; Impedance spectroscopy; Temperature dependence; Inorganic compounds; Tunnel effect; Magnetic field effects; Experimental study; Cobalt; Relaxation time; Multilayers; Sandwich compound; Discontinuous metallic thin films; Percolation; Magnetoresistance; Electric impedance; Island structure; Aluminium oxides; Equivalent circuits
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(99)00478-3

We present the impedance and its variation in magnetic fields for discontinuous Co films sandwiched by Al
2O
3. The Co nominal thickness varies from 0.7 to 2.5
nm and the room temperature impedance has been measured from fractions of Hz to 100
kHz. The samples present a distribution of relaxation times with a maximum width below the percolation point. For a given frequency, an external magnetic field induces a variation in the modulus and in the phase of the impedance. The evolution of the tunnel magnetoimpedance, whose real part is the usual tunnel magnetoresistance, as a function of frequency is presented and can be described in terms of the variations in the relaxation time.