Laser deposition of amorphous magnetic Co_(68.15)Fe_(4.35)B_(15)Si_(12.5) films: the strong effect of inhomogeneous magnetic field

摘要

Two sets of magnetic non-magnetostrictive Co_(68.12) Fe_(4.35)B_(13)Si_(12.5) films, in inhomogeneous magnetic field (nablaH approx 2.5 kOe/cm) and without any external field, were prepared by pulsed excimer laser. The films synthesized in the absence of field showed high anisotropies and coercivities, more than 30 Oe. However, the films deposited in inhomogeneous magnetic field exhibited a great improvement of coercivity, H_c approx 0.7 Oe. Moreover, the films prepared in magnetic field with the same number of laser pulses exhibited twofold increase in deposition rate per cm~2. Droplet sizes and density of the two kinds of films were also different. It semmed that the focusing of laser plume, by magnetic dipole force, which mainly consists of magnetic neutral atoms, is responsible for such effects. The observed strong color change of laser plum is the evidence of that. However, the calculations showed that the magnetic dipole force is too weak to affect on the laser plume kinetics and search for other mechanisms to explain the observed phenomena should be made.