Magnetic properties of NdFeB thin films grown by a pulsed laser deposition

Abstract

High energy product Nd 2Fe 14B films were grown on Si(1 0 0) substrate by KrF pulsed laser ablation using the targets of Nd x Fe 90.98− x B 9.02 ( x=17.51–27.51). The films of Nd 2Fe 14B single phase did not exhibit a preferred orientation. However, [2 2 1], [0 0 6] and [2 2 2] axes were prominent for the films grown at the substrate temperature above 680°C by using the target of Nd 27.51Fe 63.47B 9.02. This condition provided the superior magnetic properties along the out-of-plane direction of films resulting in the magnetic properties of 4π M s=7 kG, 4π M r=4 kG, and H c=1000 Oe. The deposition rate was not much influenced by changing the substrate temperature ( T s), but it increased linearly by increasing the beam energy density. The beam density of 3 J/cm 2 gave the optimal condition to have the highest 4π M r and H c simultaneously. The higher content of Nd induced a higher coercivity and 4π M r at the same time due to the finer grain size without prominent change in 4π M s. The films of x=27.51 showed a grain size of less than 12 nm while that of x=17.51 showed a grain size of about 15 nm.