Tunneling magnetoresistance and magnetic properties of Fe–Al2O3 nanogranular films

Abstract

Tunneling giant magnetoresistance (MR) of the Fe–Al2O3 nanogranular films has been observed over a wide range of Fe volume fraction x and it took a maximum of 4.4% at room temperature for the film with x=0.45 at H=10 kOe. Furthermore, the field dependence of MR of the samples is well described by the form proportional to the square of the magnetization. Moreover, an estimate of the magnetic anisotropy energy density Ku increases with the decrease of x, yielding a value 2 orders of magnitude greater than the value for bulk Fe when x=0.23. The Bloch’s law, MS(T)=MS0(1−BTb), can also hold for all the samples but with nonbulk parameters dependent on the Fe volume fraction. These results reveal a percolation effect on the magnetic properties, as well as the conductance, in such nanogranular films.

Structural and magnetic properties of Fe and Co nanoparticles embedded in powdered Al2O3

“…However, the scientific community is currently devoting special attention to systems displaying magnetic tunneling and superparamagnetism due to interest in their application as ultra-high-density recording media. The vast majority of reported efforts are based on either Fe or Co particles in Al 2 O 3 [25][26][27][28][29][30][31][32][33][34][35].…”