Accuracy of 45° torque method for obtaining anisotropy constant of 2D random films

Computer simulation was used to examine the accuracy of anisotropy energy constant, K-u of thin film media obtained from the 45 degrees torque method. The easy axes of the media were distributed randomly in plane. The obtained K-u value depends on range of the applied field. For 2D random media with H-K=1 similar to 40 kOe, M-s=100 similar to 600 emu/cm(3), A=0 similar to 1 x 10(-6) erg/cm, separation between adjacent grains=0 similar to 2 nm, the difference between obtained K-u value and exact K-u was at most 20%, if the range of applied field was larger than 10-20 kOe. Here, the standard values of the physical parameters were H-K=10 kOe, M-s=460 emu/cm(3), A=0, separation between adjacent grains=0, and each parameter was varied successively.