EFFECT OF ANNEALING ON CRYSTALLINE STATE AND MAGNETIC PROPERTIES OF (Tb0.28Dy0.72) Fe1.90 THIN FILMS

Giant magnetostrictive (Tb0.28Dy0.72)Fe-1.90 thin films were deposited on Si (111) substrates at room temperature by pulsed laser deposition (PLD). The crystalline state and the magnetic properties of the samples were investigated in relation to the different annealing temperatures T-a, which varied between 623K and 923K. X-ray diffraction results indicated the films are in amorphous state after annealing at T-a = 623K-823K for 1h, and were partially crystallized at T-a = 923K for 1h. Meanwhile, the annealing treatment showed a great influence on the magnetic anisotropy. The orientation of the magnetic easy axis of the as-deposited films changed from perpendicular to parallel to the film plane after annealing treatment. The mechanism of the transformation of the magnetic easy axis was explained in terms of the tensile stress which is formed due to the difference in the thermal expansion coefficients of the thin film and substrate.