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

High energy product Nd2Fe14B films were grown onto Si(100) substrate by a KrF pulsed laser ablation using the targets of NdxFe90.98-xB9.02 (x=17.51 similar to 27.51). The films of the Nd2Fe14B single phase did not exhibit a preferred orientation. However, [221], [006] and [222] axes were prominent for the films grown at the substrate temperature above 680 degrees C by using the target of Nd27.51Fe63.47B9.02. This condition provided superior magnetic properties along the out-of-plane direction of films resulting in the magnetic properties of 4 pi M-s congruent to 7 kG, 4 pi M-r congruent to 4 kG, and iH(c) congruent to 1000 Oe. The deposition rate wasn't influenced much 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) created the optimal condition for the highest 4 pi M-r and iH(c) simultaneously. The higher content of Nd induced a higher coercivity and concentration of 4 pi M-r at the same time due to the finer grain size without a prominent change in 4 pi M-s. The films of x = 27.51 exhibited a grain size of less than 12 nm while that of x = 17.51 produced a size about 15 nm.